The phone kept nagging me to update to 12 and later to 13 all the time. I didn’t manage to find a way to make the notification go away… Maybe it’s just me being a doofus. As for the notifications thing, I literally tried everything except factory resetting my phone. Guess I am just unlucky.
I wanted to get some of the Samsung apps back, but most weren’t updated to work on 12 at that time and later I just forgot and gave in. I’ve never used F-Droid before but it looks like a good time to start now. Tnx for reminding me about it.