diff --git a/MIGRATION_GUIDE.md b/MIGRATION_GUIDE.md
index d78abe14c5..7a1275b852 100644
--- a/MIGRATION_GUIDE.md
+++ b/MIGRATION_GUIDE.md
@@ -14,6 +14,7 @@ Looking to upgrade from Sentry SDK 2.x to 3.x? Here's a comprehensive list of wh
 - You can no longer change the sampled status of a span with `span.sampled = False` after starting it.
 - The `Span()` constructor does not accept a `hub` parameter anymore.
 - `Span.finish()` does not accept a `hub` parameter anymore.
+- `Span.finish()` no longer returns the `event_id` if the event is sent to sentry.
 - The `Profile()` constructor does not accept a `hub` parameter anymore.
 - A `Profile` object does not have a `.hub` property anymore.
 - `sentry_sdk.continue_trace` no longer returns a `Transaction` and is now a context manager.
@@ -146,6 +147,7 @@ Looking to upgrade from Sentry SDK 2.x to 3.x? Here's a comprehensive list of wh
 - `continue_from_headers`, `continue_from_environ` and `from_traceparent` have been removed, please use top-level API `sentry_sdk.continue_trace` instead.
 - `PropagationContext` constructor no longer takes a `dynamic_sampling_context` but takes a `baggage` object instead.
 - `ThreadingIntegration` no longer takes the `propagate_hub` argument.
+- `Baggage.populate_from_transaction` has been removed.
 
 ### Deprecated
 
diff --git a/sentry_sdk/client.py b/sentry_sdk/client.py
index 796da2614e..85623d8056 100644
--- a/sentry_sdk/client.py
+++ b/sentry_sdk/client.py
@@ -449,7 +449,7 @@ def _prepare_event(
                         )
                 return None
 
-            event = event_
+            event = event_  # type: Optional[Event]  # type: ignore[no-redef]
 
             spans_delta = spans_before - len(event.get("spans", []))
             if is_transaction and spans_delta > 0 and self.transport is not None:
@@ -483,7 +483,7 @@ def _prepare_event(
 
         for key in "release", "environment", "server_name", "dist":
             if event.get(key) is None and self.options[key] is not None:
-                event[key] = str(self.options[key]).strip()
+                event[key] = str(self.options[key]).strip()  # type: ignore[literal-required]
         if event.get("sdk") is None:
             sdk_info = dict(SDK_INFO)
             sdk_info["integrations"] = sorted(self.integrations.keys())
@@ -523,7 +523,7 @@ def _prepare_event(
             and event is not None
             and event.get("type") != "transaction"
         ):
-            new_event = None
+            new_event = None  # type: Optional[Event]
             with capture_internal_exceptions():
                 new_event = before_send(event, hint or {})
             if new_event is None:
@@ -532,7 +532,7 @@ def _prepare_event(
                     self.transport.record_lost_event(
                         "before_send", data_category="error"
                     )
-            event = new_event
+            event = new_event  # type: Optional[Event]  # type: ignore[no-redef]
 
         before_send_transaction = self.options["before_send_transaction"]
         if (
@@ -562,7 +562,7 @@ def _prepare_event(
                         reason="before_send", data_category="span", quantity=spans_delta
                     )
 
-            event = new_event
+            event = new_event  # type: Optional[Event]  # type: ignore[no-redef]
 
         return event
 
diff --git a/sentry_sdk/integrations/asyncpg.py b/sentry_sdk/integrations/asyncpg.py
index 35726658ed..65f4d30e0d 100644
--- a/sentry_sdk/integrations/asyncpg.py
+++ b/sentry_sdk/integrations/asyncpg.py
@@ -189,7 +189,7 @@ async def _inner(*args: Any, **kwargs: Any) -> T:
 
 def _get_db_data(
     conn: Any = None,
-    addr: Optional[tuple[str]] = None,
+    addr: Optional[tuple[str, ...]] = None,
     database: Optional[str] = None,
     user: Optional[str] = None,
 ) -> dict[str, str]:
@@ -218,6 +218,6 @@ def _get_db_data(
     return data
 
 
-def _set_on_span(span: Span, data: dict[str, Any]):
+def _set_on_span(span: Span, data: dict[str, Any]) -> None:
     for key, value in data.items():
         span.set_attribute(key, value)
diff --git a/sentry_sdk/integrations/clickhouse_driver.py b/sentry_sdk/integrations/clickhouse_driver.py
index d43603ba2f..7c908b7d6d 100644
--- a/sentry_sdk/integrations/clickhouse_driver.py
+++ b/sentry_sdk/integrations/clickhouse_driver.py
@@ -9,7 +9,7 @@
     ensure_integration_enabled,
 )
 
-from typing import TYPE_CHECKING, Any, Dict, TypeVar
+from typing import TYPE_CHECKING, cast, Any, Dict, TypeVar
 
 # Hack to get new Python features working in older versions
 # without introducing a hard dependency on `typing_extensions`
@@ -94,6 +94,7 @@ def _inner(*args: P.args, **kwargs: P.kwargs) -> T:
         connection._sentry_span = span  # type: ignore[attr-defined]
 
         data = _get_db_data(connection)
+        data = cast("dict[str, Any]", data)
         data["db.query.text"] = query
 
         if query_id:
@@ -116,9 +117,10 @@ def _inner(*args: P.args, **kwargs: P.kwargs) -> T:
 def _wrap_end(f: Callable[P, T]) -> Callable[P, T]:
     def _inner_end(*args: P.args, **kwargs: P.kwargs) -> T:
         res = f(*args, **kwargs)
-        connection = args[0].connection
+        client = cast("clickhouse_driver.client.Client", args[0])
+        connection = client.connection
 
-        span = getattr(connection, "_sentry_span", None)  # type: ignore[attr-defined]
+        span = getattr(connection, "_sentry_span", None)
         if span is not None:
             data = getattr(connection, "_sentry_db_data", {})
 
@@ -148,8 +150,9 @@ def _inner_end(*args: P.args, **kwargs: P.kwargs) -> T:
 
 def _wrap_send_data(f: Callable[P, T]) -> Callable[P, T]:
     def _inner_send_data(*args: P.args, **kwargs: P.kwargs) -> T:
-        connection = args[0].connection
-        db_params_data = args[2]
+        client = cast("clickhouse_driver.client.Client", args[0])
+        connection = client.connection
+        db_params_data = cast("list[Any]", args[2])
         span = getattr(connection, "_sentry_span", None)
 
         if span is not None:
@@ -157,8 +160,10 @@ def _inner_send_data(*args: P.args, **kwargs: P.kwargs) -> T:
             _set_on_span(span, data)
 
             if should_send_default_pii():
-                saved_db_data = getattr(connection, "_sentry_db_data", {})
-                db_params = saved_db_data.get("db.params") or []
+                saved_db_data = getattr(
+                    connection, "_sentry_db_data", {}
+                )  # type: dict[str, Any]
+                db_params = saved_db_data.get("db.params") or []  # type: list[Any]
                 db_params.extend(db_params_data)
                 saved_db_data["db.params"] = db_params
                 span.set_attribute("db.params", _serialize_span_attribute(db_params))
@@ -178,6 +183,6 @@ def _get_db_data(connection: clickhouse_driver.connection.Connection) -> Dict[st
     }
 
 
-def _set_on_span(span: Span, data: Dict[str, Any]):
+def _set_on_span(span: Span, data: Dict[str, Any]) -> None:
     for key, value in data.items():
         span.set_attribute(key, _serialize_span_attribute(value))
diff --git a/sentry_sdk/integrations/opentelemetry/integration.py b/sentry_sdk/integrations/opentelemetry/integration.py
index 551ef48891..1124e736ed 100644
--- a/sentry_sdk/integrations/opentelemetry/integration.py
+++ b/sentry_sdk/integrations/opentelemetry/integration.py
@@ -59,10 +59,10 @@ def _patch_readable_span():
     def sentry_patched_readable_span(self):
         # type: (Span) -> ReadableSpan
         readable_span = old_readable_span(self)
-        readable_span._sentry_meta = getattr(self, "_sentry_meta", {})
+        readable_span._sentry_meta = getattr(self, "_sentry_meta", {})  # type: ignore[attr-defined]
         return readable_span
 
-    Span._readable_span = sentry_patched_readable_span
+    Span._readable_span = sentry_patched_readable_span  # type: ignore[method-assign]
 
 
 def _setup_sentry_tracing():
diff --git a/sentry_sdk/integrations/opentelemetry/sampler.py b/sentry_sdk/integrations/opentelemetry/sampler.py
index 8d886add09..0b7004dc34 100644
--- a/sentry_sdk/integrations/opentelemetry/sampler.py
+++ b/sentry_sdk/integrations/opentelemetry/sampler.py
@@ -132,10 +132,15 @@ def should_sample(
         # parent_span_context.is_valid means this span has a parent, remote or local
         is_root_span = not parent_span_context.is_valid or parent_span_context.is_remote
 
+        sample_rate = None
+
         # Explicit sampled value provided at start_span
-        if attributes.get(SentrySpanAttribute.CUSTOM_SAMPLED) is not None:
+        custom_sampled = cast(
+            "Optional[bool]", attributes.get(SentrySpanAttribute.CUSTOM_SAMPLED)
+        )
+        if custom_sampled is not None:
             if is_root_span:
-                sample_rate = float(attributes[SentrySpanAttribute.CUSTOM_SAMPLED])
+                sample_rate = float(custom_sampled)
                 if sample_rate > 0:
                     return sampled_result(parent_span_context, attributes, sample_rate)
                 else:
@@ -145,8 +150,6 @@ def should_sample(
                     f"[Tracing] Ignoring sampled param for non-root span {name}"
                 )
 
-        sample_rate = None
-
         # Check if there is a traces_sampler
         # Traces_sampler is responsible to check parent sampled to have full transactions.
         has_traces_sampler = callable(client.options.get("traces_sampler"))
@@ -190,16 +193,19 @@ def get_description(self) -> str:
 
 
 def create_sampling_context(name, attributes, parent_span_context, trace_id):
-    # type: (str, Attributes, SpanContext, str) -> dict[str, Any]
+    # type: (str, Attributes, Optional[SpanContext], int) -> dict[str, Any]
     sampling_context = {
         "transaction_context": {
             "name": name,
-            "op": attributes.get(SentrySpanAttribute.OP),
-            "source": attributes.get(SentrySpanAttribute.SOURCE),
+            "op": attributes.get(SentrySpanAttribute.OP) if attributes else None,
+            "source": (
+                attributes.get(SentrySpanAttribute.SOURCE) if attributes else None
+            ),
         },
         "parent_sampled": get_parent_sampled(parent_span_context, trace_id),
-    }
+    }  # type: dict[str, Any]
 
-    sampling_context.update(attributes)
+    if attributes is not None:
+        sampling_context.update(attributes)
 
     return sampling_context
diff --git a/sentry_sdk/integrations/opentelemetry/utils.py b/sentry_sdk/integrations/opentelemetry/utils.py
index 1db3f65da1..d890849c31 100644
--- a/sentry_sdk/integrations/opentelemetry/utils.py
+++ b/sentry_sdk/integrations/opentelemetry/utils.py
@@ -18,8 +18,12 @@
 import sentry_sdk
 from sentry_sdk.utils import Dsn
 from sentry_sdk.consts import SPANSTATUS, OP, SPANDATA
-from sentry_sdk.tracing import get_span_status_from_http_code, DEFAULT_SPAN_ORIGIN
-from sentry_sdk.tracing_utils import Baggage, LOW_QUALITY_TRANSACTION_SOURCES
+from sentry_sdk.tracing import (
+    get_span_status_from_http_code,
+    DEFAULT_SPAN_ORIGIN,
+    LOW_QUALITY_TRANSACTION_SOURCES,
+)
+from sentry_sdk.tracing_utils import Baggage
 from sentry_sdk.integrations.opentelemetry.consts import SentrySpanAttribute
 
 from sentry_sdk._types import TYPE_CHECKING
diff --git a/sentry_sdk/tracing.py b/sentry_sdk/tracing.py
index e67301e1a7..7b534d7efd 100644
--- a/sentry_sdk/tracing.py
+++ b/sentry_sdk/tracing.py
@@ -266,7 +266,7 @@ def finish(
         scope=None,  # type: Optional[sentry_sdk.Scope]
         end_timestamp=None,  # type: Optional[Union[float, datetime]]
     ):
-        # type: (...) -> Optional[str]
+        # type: (...) -> None
         pass
 
     def set_measurement(self, name, value, unit=""):
@@ -375,7 +375,9 @@ def __init__(
                     self.set_status(status)
 
     def __eq__(self, other):
-        # type: (Span) -> bool
+        # type: (object) -> bool
+        if not isinstance(other, Span):
+            return False
         return self._otel_span == other._otel_span
 
     def __repr__(self):
@@ -526,7 +528,6 @@ def sample_rate(self):
         sample_rate = self._otel_span.get_span_context().trace_state.get(
             TRACESTATE_SAMPLE_RATE_KEY
         )
-        sample_rate = cast("Optional[str]", sample_rate)
         return float(sample_rate) if sample_rate is not None else None
 
     @property
@@ -668,18 +669,24 @@ def set_data(self, key, value):
 
     def get_attribute(self, name):
         # type: (str) -> Optional[Any]
-        if not isinstance(self._otel_span, ReadableSpan):
+        if (
+            not isinstance(self._otel_span, ReadableSpan)
+            or not self._otel_span.attributes
+        ):
             return None
         return self._otel_span.attributes.get(name)
 
     def set_attribute(self, key, value):
         # type: (str, Any) -> None
+        # otel doesn't support None as values, preferring to not set the key
+        # at all instead
         if value is None:
-            # otel doesn't support None as values, preferring to not set the key
-            # at all instead
+            return
+        serialized_value = _serialize_span_attribute(value)
+        if serialized_value is None:
             return
 
-        self._otel_span.set_attribute(key, _serialize_span_attribute(value))
+        self._otel_span.set_attribute(key, serialized_value)
 
     @property
     def status(self):
@@ -690,7 +697,7 @@ def status(self):
         Sentry `SPANSTATUS` it can not be guaranteed that the status
         set in `set_status()` will be the same as the one returned here.
         """
-        if not hasattr(self._otel_span, "status"):
+        if not isinstance(self._otel_span, ReadableSpan):
             return None
 
         if self._otel_span.status.status_code == StatusCode.UNSET:
@@ -740,10 +747,10 @@ def set_http_status(self, http_status):
 
     def is_success(self):
         # type: () -> bool
-        return self._otel_span.status.code == StatusCode.OK
+        return self.status == SPANSTATUS.OK
 
     def finish(self, end_timestamp=None):
-        # type: (Optional[Union[float, datetime]]) -> Optional[str]
+        # type: (Optional[Union[float, datetime]]) -> None
         if end_timestamp is not None:
             from sentry_sdk.integrations.opentelemetry.utils import (
                 convert_to_otel_timestamp,
diff --git a/sentry_sdk/tracing_utils.py b/sentry_sdk/tracing_utils.py
index 6ebe7e0322..952ffccc4c 100644
--- a/sentry_sdk/tracing_utils.py
+++ b/sentry_sdk/tracing_utils.py
@@ -525,52 +525,6 @@ def from_options(cls, scope):
 
         return Baggage(sentry_items, third_party_items, mutable)
 
-    @classmethod
-    def populate_from_transaction(cls, transaction):
-        # type: (sentry_sdk.tracing.Transaction) -> Baggage
-        """
-        Populate fresh baggage entry with sentry_items and make it immutable
-        if this is the head SDK which originates traces.
-        """
-        client = sentry_sdk.get_client()
-        sentry_items = {}  # type: Dict[str, str]
-
-        if not client.is_active():
-            return Baggage(sentry_items)
-
-        options = client.options or {}
-
-        sentry_items["trace_id"] = transaction.trace_id
-
-        if options.get("environment"):
-            sentry_items["environment"] = options["environment"]
-
-        if options.get("release"):
-            sentry_items["release"] = options["release"]
-
-        if options.get("dsn"):
-            sentry_items["public_key"] = Dsn(options["dsn"]).public_key
-
-        if (
-            transaction.name
-            and transaction.source not in LOW_QUALITY_TRANSACTION_SOURCES
-        ):
-            sentry_items["transaction"] = transaction.name
-
-        if transaction.sample_rate is not None:
-            sentry_items["sample_rate"] = str(transaction.sample_rate)
-
-        if transaction.sampled is not None:
-            sentry_items["sampled"] = "true" if transaction.sampled else "false"
-
-        # there's an existing baggage but it was mutable,
-        # which is why we are creating this new baggage.
-        # However, if by chance the user put some sentry items in there, give them precedence.
-        if transaction._baggage and transaction._baggage.sentry_items:
-            sentry_items.update(transaction._baggage.sentry_items)
-
-        return Baggage(sentry_items, mutable=False)
-
     def freeze(self):
         # type: () -> None
         self.mutable = False
@@ -722,6 +676,5 @@ def get_current_span(scope=None):
 # Circular imports
 from sentry_sdk.tracing import (
     BAGGAGE_HEADER_NAME,
-    LOW_QUALITY_TRANSACTION_SOURCES,
     SENTRY_TRACE_HEADER_NAME,
 )
diff --git a/sentry_sdk/transport.py b/sentry_sdk/transport.py
index 278a0a43d0..99251cf439 100644
--- a/sentry_sdk/transport.py
+++ b/sentry_sdk/transport.py
@@ -23,7 +23,7 @@
 from sentry_sdk.worker import BackgroundWorker
 from sentry_sdk.envelope import Envelope, Item, PayloadRef
 
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, cast
 
 if TYPE_CHECKING:
     from typing import Any
@@ -179,6 +179,7 @@ def _parse_rate_limits(header, now=None):
 
             retry_after = now + timedelta(seconds=int(retry_after_val))
             for category in categories and categories.split(";") or (None,):
+                category = cast("Optional[EventDataCategory]", category)
                 yield category, retry_after
         except (LookupError, ValueError):
             continue