I'd recommend 2021 if you have issues on 2020. I know more recent mac's have issues with 2020, so might be the same for linux. There's lots of people in the discord running 2021 without issues. There are known issues with various powerquest things in versions later than that though. The games should play fine, but there's annoying editor issues that will mess you around when you encounter them unexpectedly down the track.
I'm in no rush to upgrade the base version at the moment, since there's practically nothing added that's useful for usual powerquest games, and it does run significantly slower with each version :P And since users actually get nothing out of "unity support" it's kinda pointless spending time re-fixing unity issues each time they update to try and keep updated. I frequently wish I was back on 2017 ha ha. Unity will always suggest you use the latest though since that's how they make money, I just wished they would focus on improving things rather than tacking on extra half-baked features ;)