It's possible to get push notifications from left rooms

If I wanted to follow along I wouldn't've left the room in the first place.

To reproduce:

1. Configure some keywords to cause notifications
2. Join a room
3. Decide you don't like the room anymore
4. Leave the room
5. Someone still in the room sends a message containing at least one of the configured keywords
6. You get a push notification for that message even though you shouldn't

Might require another user on your HS to still be in the room, not sure.