To be fair, the Steam Deck support level is a bit arbitrary and some Verified games may work worse than some Untested games. The only game that I had an issue

To be fair, the Steam Deck support level is a bit arbitrary and some Verified games may work worse than some Untested games. The only game that I had an issue with is The Unfinished Swan which I bought on Steam after having enjoyed playing it on a PS3 (good enough to buy twice). I couldn't get it to work initially with it just going to a blank screen (not the game itself which ironically does start with an all white screen) no matter my tinkering with Proton versions. However, tried it again a few months ago and it worked perfectly with default settings.