Since Android 10 the OS has really gone downhill IMO.
IIRC they have also been ripping out workarounds that people use to keep their apps open, so expect things like Syncthing/OpenVPN/Element/Termux etc to no longer be able to survive in the background - I believe the non dismissable notifications are a part of that too. To me this also means apps using their own push services are now being forced into a position where they’ll need to consider Google Cloud Messaging.
The OpenVPN one is pretty poor because unless you have it set to be always-on, Android can kill it freely now, then completely bypass your VPN preference because “it’s not working”
These new changes in A14 kind of show everything wrong with having an ad company in charge of a mobile OS