Maybe actually fix time comparison

mautrix_telegram/user.py

@@ -695,12 +695,12 @@ class User(DBUser, AbstractUser, BaseUser):
                 self.log.exception(f"Error while creating {portal.tgid_log}")
         if portal.mxid and puppet and puppet.is_real_user:
             tg_space = portal.tgid if portal.peer_type == "channel" else self.tgid
-            last_message_date: datetime = cast(datetime, dialog.date)
+            last_message_date: float = cast(datetime, dialog.date).timestamp()
             unread_threshold_hours = self.config["bridge.backfill.unread_hours_threshold"]
             force_read = (
                 was_created
                 and unread_threshold_hours >= 0
-                and last_message_date + timedelta(hours=unread_threshold_hours) < datetime.utcnow()
+                and last_message_date + (unread_threshold_hours * 60 * 60) < time.time()
             )
             if dialog.unread_count == 0 or force_read:
                 # This is usually more reliable than finding a specific message
@@ -709,7 +709,7 @@ class User(DBUser, AbstractUser, BaseUser):
                 if force_read:
                     self.log.debug(
                         f"Marking {portal.tgid_log} as read because the last message is from "
-                        f"{last_message_date} (unread threshold is {unread_threshold_hours} hours)"
+                        f"{dialog.date} (unread threshold is {unread_threshold_hours} hours)"
                     )
             else:
                 last_read = await DBMessage.get_one_by_tgid(