diff --git a/pydantic_settings/sources.py b/pydantic_settings/sources.py
index 09c74560..b6f0f646 100644
--- a/pydantic_settings/sources.py
+++ b/pydantic_settings/sources.py
@@ -41,14 +41,15 @@
 from dotenv import dotenv_values
 from pydantic import AliasChoices, AliasPath, BaseModel, Json, RootModel, Secret, TypeAdapter
 from pydantic._internal._repr import Representation
-from pydantic._internal._typing_extra import WithArgsTypes, origin_is_union, typing_base
-from pydantic._internal._utils import deep_update, is_model_class, lenient_issubclass
+from pydantic._internal._utils import deep_update, is_model_class
 from pydantic.dataclasses import is_pydantic_dataclass
 from pydantic.fields import FieldInfo
 from pydantic_core import PydanticUndefined
-from typing_extensions import _AnnotatedAlias, get_args, get_origin
+from typing_extensions import get_args, get_origin
+from typing_inspection import typing_objects
+from typing_inspection.introspection import is_union_origin
 
-from pydantic_settings.utils import path_type_label
+from pydantic_settings.utils import _lenient_issubclass, _WithArgsTypes, path_type_label
 
 if TYPE_CHECKING:
     if sys.version_info >= (3, 11):
@@ -484,7 +485,7 @@ def _extract_field_info(self, field: FieldInfo, field_name: str) -> list[tuple[s
                 field_info.append((v_alias, self._apply_case_sensitive(v_alias), False))
 
         if not v_alias or self.config.get('populate_by_name', False):
-            if origin_is_union(get_origin(field.annotation)) and _union_is_complex(field.annotation, field.metadata):
+            if is_union_origin(get_origin(field.annotation)) and _union_is_complex(field.annotation, field.metadata):
                 field_info.append((field_name, self._apply_case_sensitive(self.env_prefix + field_name), True))
             else:
                 field_info.append((field_name, self._apply_case_sensitive(self.env_prefix + field_name), False))
@@ -530,12 +531,13 @@ class Settings(BaseSettings):
             annotation = field.annotation
 
             # If field is Optional, we need to find the actual type
-            args = get_args(annotation)
-            if origin_is_union(get_origin(field.annotation)) and len(args) == 2 and type(None) in args:
-                for arg in args:
-                    if arg is not None:
-                        annotation = arg
-                        break
+            if is_union_origin(get_origin(field.annotation)):
+                args = get_args(annotation)
+                if len(args) == 2 and type(None) in args:
+                    for arg in args:
+                        if arg is not None:
+                            annotation = arg
+                            break
 
             # This is here to make mypy happy
             # Item "None" of "Optional[Type[Any]]" has no attribute "model_fields"
@@ -553,7 +555,7 @@ class Settings(BaseSettings):
                 values[name] = value
                 continue
 
-            if lenient_issubclass(sub_model_field.annotation, BaseModel) and isinstance(value, dict):
+            if _lenient_issubclass(sub_model_field.annotation, BaseModel) and isinstance(value, dict):
                 values[sub_model_field_name] = self._replace_field_names_case_insensitively(sub_model_field, value)
             else:
                 values[sub_model_field_name] = value
@@ -623,7 +625,7 @@ def __call__(self) -> dict[str, Any]:
                         field_value = None
                 if (
                     not self.case_sensitive
-                    # and lenient_issubclass(field.annotation, BaseModel)
+                    # and _lenient_issubclass(field.annotation, BaseModel)
                     and isinstance(field_value, dict)
                 ):
                     data[field_key] = self._replace_field_names_case_insensitively(field, field_value)
@@ -842,7 +844,7 @@ def _field_is_complex(self, field: FieldInfo) -> tuple[bool, bool]:
         """
         if self.field_is_complex(field):
             allow_parse_failure = False
-        elif origin_is_union(get_origin(field.annotation)) and _union_is_complex(field.annotation, field.metadata):
+        elif is_union_origin(get_origin(field.annotation)) and _union_is_complex(field.annotation, field.metadata):
             allow_parse_failure = True
         else:
             return False, False
@@ -888,12 +890,11 @@ class Cfg(BaseSettings):
             return None
 
         annotation = field.annotation if isinstance(field, FieldInfo) else field
-        if origin_is_union(get_origin(annotation)) or isinstance(annotation, WithArgsTypes):
-            for type_ in get_args(annotation):
-                type_has_key = self.next_field(type_, key, case_sensitive)
-                if type_has_key:
-                    return type_has_key
-        elif is_model_class(annotation) or is_pydantic_dataclass(annotation):
+        for type_ in get_args(annotation):
+            type_has_key = self.next_field(type_, key, case_sensitive)
+            if type_has_key:
+                return type_has_key
+        if is_model_class(annotation) or is_pydantic_dataclass(annotation):
             fields = _get_model_fields(annotation)
             # `case_sensitive is None` is here to be compatible with the old behavior.
             # Has to be removed in V3.
@@ -923,7 +924,8 @@ def explode_env_vars(self, field_name: str, field: FieldInfo, env_vars: Mapping[
         if not self.env_nested_delimiter:
             return {}
 
-        is_dict = lenient_issubclass(get_origin(field.annotation), dict)
+        ann = field.annotation
+        is_dict = ann is dict or _lenient_issubclass(get_origin(ann), dict)
 
         prefixes = [
             f'{env_name}{self.env_nested_delimiter}' for _, env_name, _ in self._extract_field_info(field, field_name)
@@ -1065,7 +1067,7 @@ def __call__(self) -> dict[str, Any]:
                         (
                             _annotation_is_complex(field.annotation, field.metadata)
                             or (
-                                origin_is_union(get_origin(field.annotation))
+                                is_union_origin(get_origin(field.annotation))
                                 and _union_is_complex(field.annotation, field.metadata)
                             )
                         )
@@ -1382,7 +1384,7 @@ def _get_merge_parsed_list_types(
         merge_type = self._cli_dict_args.get(field_name, list)
         if (
             merge_type is list
-            or not origin_is_union(get_origin(merge_type))
+            or not is_union_origin(get_origin(merge_type))
             or not any(
                 type_
                 for type_ in get_args(merge_type)
@@ -1526,7 +1528,7 @@ def _sort_arg_fields(self, model: type[BaseModel]) -> list[tuple[str, FieldInfo]
                     alias_names, *_ = _get_alias_names(field_name, field_info)
                     if len(alias_names) > 1:
                         raise SettingsError(f'subcommand argument {model.__name__}.{field_name} has multiple aliases')
-                    field_types = [type_ for type_ in get_args(field_info.annotation) if type_ is not type(None)]
+                    field_types = (type_ for type_ in get_args(field_info.annotation) if type_ is not type(None))
                     for field_type in field_types:
                         if not (is_model_class(field_type) or is_pydantic_dataclass(field_type)):
                             raise SettingsError(
@@ -1984,19 +1986,20 @@ def _metavar_format_recurse(self, obj: Any) -> str:
             return '...'
         elif isinstance(obj, Representation):
             return repr(obj)
-        elif isinstance(obj, typing_extensions.TypeAliasType):
+        elif typing_objects.is_typealiastype(obj):
             return str(obj)
 
-        if not isinstance(obj, (typing_base, WithArgsTypes, type)):
+        origin = get_origin(obj)
+        if origin is None and not isinstance(obj, (type, typing.ForwardRef, typing_extensions.ForwardRef)):
             obj = obj.__class__
 
-        if origin_is_union(get_origin(obj)):
+        if is_union_origin(origin):
             return self._metavar_format_choices(list(map(self._metavar_format_recurse, self._get_modified_args(obj))))
-        elif get_origin(obj) in (typing_extensions.Literal, typing.Literal):
+        elif typing_objects.is_literal(origin):
             return self._metavar_format_choices(list(map(str, self._get_modified_args(obj))))
-        elif lenient_issubclass(obj, Enum):
+        elif _lenient_issubclass(obj, Enum):
             return self._metavar_format_choices([val.name for val in obj])
-        elif isinstance(obj, WithArgsTypes):
+        elif isinstance(obj, _WithArgsTypes):
             return self._metavar_format_choices(
                 list(map(self._metavar_format_recurse, self._get_modified_args(obj))),
                 obj_qualname=obj.__qualname__ if hasattr(obj, '__qualname__') else str(obj),
@@ -2292,25 +2295,22 @@ def read_env_file(
 def _annotation_is_complex(annotation: type[Any] | None, metadata: list[Any]) -> bool:
     # If the model is a root model, the root annotation should be used to
     # evaluate the complexity.
-    try:
-        if annotation is not None and issubclass(annotation, RootModel):
-            # In some rare cases (see test_root_model_as_field),
-            # the root attribute is not available. For these cases, python 3.8 and 3.9
-            # return 'RootModelRootType'.
-            root_annotation = annotation.__annotations__.get('root', None)
-            if root_annotation is not None and root_annotation != 'RootModelRootType':
-                annotation = root_annotation
-    except TypeError:
-        pass
+    if annotation is not None and _lenient_issubclass(annotation, RootModel) and annotation is not RootModel:
+        annotation = cast('type[RootModel[Any]]', annotation)
+        root_annotation = annotation.model_fields['root'].annotation
+        if root_annotation is not None:
+            annotation = root_annotation
 
     if any(isinstance(md, Json) for md in metadata):  # type: ignore[misc]
         return False
+
+    origin = get_origin(annotation)
+
     # Check if annotation is of the form Annotated[type, metadata].
-    if isinstance(annotation, _AnnotatedAlias):
+    if typing_objects.is_annotated(origin):
         # Return result of recursive call on inner type.
         inner, *meta = get_args(annotation)
         return _annotation_is_complex(inner, meta)
-    origin = get_origin(annotation)
 
     if origin is Secret:
         return False
@@ -2324,12 +2324,12 @@ def _annotation_is_complex(annotation: type[Any] | None, metadata: list[Any]) ->
 
 
 def _annotation_is_complex_inner(annotation: type[Any] | None) -> bool:
-    if lenient_issubclass(annotation, (str, bytes)):
+    if _lenient_issubclass(annotation, (str, bytes)):
         return False
 
-    return lenient_issubclass(annotation, (BaseModel, Mapping, Sequence, tuple, set, frozenset, deque)) or is_dataclass(
-        annotation
-    )
+    return _lenient_issubclass(
+        annotation, (BaseModel, Mapping, Sequence, tuple, set, frozenset, deque)
+    ) or is_dataclass(annotation)
 
 
 def _union_is_complex(annotation: type[Any] | None, metadata: list[Any]) -> bool:
@@ -2353,14 +2353,15 @@ def _annotation_contains_types(
 
 
 def _strip_annotated(annotation: Any) -> Any:
-    while get_origin(annotation) == Annotated:
-        annotation = get_args(annotation)[0]
-    return annotation
+    if typing_objects.is_annotated(get_origin(annotation)):
+        return annotation.__origin__
+    else:
+        return annotation
 
 
 def _annotation_enum_val_to_name(annotation: type[Any] | None, value: Any) -> Optional[str]:
     for type_ in (annotation, get_origin(annotation), *get_args(annotation)):
-        if lenient_issubclass(type_, Enum):
+        if _lenient_issubclass(type_, Enum):
             if value in tuple(val.value for val in type_):
                 return type_(value).name
     return None
@@ -2368,7 +2369,7 @@ def _annotation_enum_val_to_name(annotation: type[Any] | None, value: Any) -> Op
 
 def _annotation_enum_name_to_val(annotation: type[Any] | None, name: Any) -> Any:
     for type_ in (annotation, get_origin(annotation), *get_args(annotation)):
-        if lenient_issubclass(type_, Enum):
+        if _lenient_issubclass(type_, Enum):
             if name in tuple(val.name for val in type_):
                 return type_[name]
     return None
diff --git a/pydantic_settings/utils.py b/pydantic_settings/utils.py
index 35dceea2..d4326b59 100644
--- a/pydantic_settings/utils.py
+++ b/pydantic_settings/utils.py
@@ -1,4 +1,9 @@
+import sys
+import types
 from pathlib import Path
+from typing import Any, _GenericAlias  # type: ignore [attr-defined]
+
+from typing_extensions import get_origin
 
 _PATH_TYPE_LABELS = {
     Path.is_dir: 'directory',
@@ -22,3 +27,22 @@ def path_type_label(p: Path) -> str:
             return name
 
     return 'unknown'
+
+
+# TODO remove and replace usage by `isinstance(cls, type) and issubclass(cls, class_or_tuple)`
+# once we drop support for Python 3.10.
+def _lenient_issubclass(cls: Any, class_or_tuple: Any) -> bool:  # pragma: no cover
+    try:
+        return isinstance(cls, type) and issubclass(cls, class_or_tuple)
+    except TypeError:
+        if get_origin(cls) is not None:
+            # Up until Python 3.10, isinstance(<generic_alias>, type) is True
+            # (e.g. list[int])
+            return False
+        raise
+
+
+if sys.version_info < (3, 10):
+    _WithArgsTypes = tuple()
+else:
+    _WithArgsTypes = (_GenericAlias, types.GenericAlias, types.UnionType)
diff --git a/pyproject.toml b/pyproject.toml
index ee1d7131..d3b1c8f3 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -42,6 +42,7 @@ requires-python = '>=3.9'
 dependencies = [
     'pydantic>=2.7.0',
     'python-dotenv>=0.21.0',
+    'typing-inspection>=0.4.0',
 ]
 dynamic = ['version']
 
diff --git a/requirements/pyproject.txt b/requirements/pyproject.txt
index ace5a5c2..e94dce4b 100644
--- a/requirements/pyproject.txt
+++ b/requirements/pyproject.txt
@@ -1,5 +1,5 @@
 #
-# This file is autogenerated by pip-compile with Python 3.8
+# This file is autogenerated by pip-compile with Python 3.13
 # by the following command:
 #
 #    pip-compile --extra=azure-key-vault --extra=toml --extra=yaml --no-emit-index-url --output-file=requirements/pyproject.txt pyproject.toml
@@ -63,11 +63,13 @@ tomli==2.0.1
     # via pydantic-settings (pyproject.toml)
 typing-extensions==4.12.2
     # via
-    #   annotated-types
     #   azure-core
     #   azure-identity
     #   azure-keyvault-secrets
     #   pydantic
     #   pydantic-core
+    #   typing-inspection
+typing-inspection==0.4.0
+    # via pydantic-settings (pyproject.toml)
 urllib3==2.2.2
     # via requests