fix: convert aware expiration datetimes to UTC

HISTORY.md

@@ -3,6 +3,7 @@
 ## Not released
 
 - Dropped Python 3.9 and 3.10 support due to the EOL.
+- Fixed `expire_after` datetimes with a non-UTC timezone, which lost their UTC offset instead of being converted to UTC.
 - Fixed cache key collisions between distinct JSON request bodies. Cache keys now use the
   configured JSON serializer, including bytes serializers.
 - Fixed cache key collisions between request bodies, such as `data=b'false'` and `json=False`, and between request bodies and headers. Existing cache entries won't be reused after upgrading.

aiohttp_client_cache/cache_control.py

@@ -243,8 +243,7 @@ def convert_to_utc_naive(dt: datetime):
     datetimes to the same format.
     """
     if dt.tzinfo:
-        dt.astimezone(UTC)
-        dt = dt.replace(tzinfo=None)
+        dt = dt.astimezone(UTC).replace(tzinfo=None)
     return dt
 
 

test/unit/test_cache_control.py

@@ -3,7 +3,7 @@
 import os
 from collections.abc import Mapping
 from contextlib import nullcontext
-from datetime import UTC, datetime, timedelta
+from datetime import UTC, datetime, timedelta, timezone
 from email.utils import format_datetime
 from typing import Any
 from unittest.mock import MagicMock, patch
@@ -333,6 +333,10 @@ def test_split_kv_directive(value, expected_output) -> None:
             RANDOM_DATETIME_NOW_UTC.replace(tzinfo=None),
             RANDOM_DATETIME_NOW_UTC.replace(tzinfo=None),
         ),
+        (
+            datetime(2026, 1, 1, 12, tzinfo=timezone(timedelta(hours=2))),
+            datetime(2026, 1, 1, 10),
+        ),
     ],
 )
 def test_convert_to_utc_naive(dt: datetime, dt_utc: datetime) -> None: