chore: Improve websocket behavior with unsynched time

closes freqtrade#11139

Author: xmatthias

freqtrade/exchange/exchange_ws.py

@@ -11,7 +11,7 @@
 from freqtrade.enums.candletype import CandleType
 from freqtrade.exchange.exchange import timeframe_to_seconds
 from freqtrade.exchange.exchange_types import OHLCVResponse
-from freqtrade.util import dt_ts, format_ms_time
+from freqtrade.util import dt_ts, format_ms_time, format_ms_time_det
 
 
 logger = logging.getLogger(__name__)
@@ -180,15 +180,18 @@ async def get_ohlcv(
         # Deepcopy the response - as it might be modified in the background as new messages arrive
         candles = deepcopy(self.ccxt_object.ohlcvs.get(pair, {}).get(timeframe))
         refresh_date = self.klines_last_refresh[(pair, timeframe, candle_type)]
-        drop_hint = False
-        if refresh_date > candle_ts:
-            # Refreshed after candle was complete.
-            # logger.info(f"{candles[-1][0]} >= {candle_date}")
-            drop_hint = candles[-1][0] >= candle_ts
+        received_ts = candles[-1][0] if candles else 0
+        drop_hint = received_ts >= candle_ts
+        if received_ts > refresh_date:
+            logger.warning(
+                f"{pair}, {timeframe} - Candle date > last refresh "
+                f"({format_ms_time(received_ts)} > {format_ms_time_det(refresh_date)}). "
+                "This usually suggests a problem with time synchronization."
+            )
         logger.debug(
             f"watch result for {pair}, {timeframe} with length {len(candles)}, "
-            f"{format_ms_time(candles[-1][0])}, "
-            f"lref={format_ms_time(refresh_date)}, "
+            f"r_ts={format_ms_time(received_ts)}, "
+            f"lref={format_ms_time_det(refresh_date)}, "
             f"candle_ts={format_ms_time(candle_ts)}, {drop_hint=}"
         )
         return pair, timeframe, candle_type, candles, drop_hint