I’ve not found a problem with those games verified by Steam
That’s a pertinent point.. the steam deck runs some flavour of Linux, with steam OS on top of it, rather than running MS windows with a steam client installed.
Most games on the steam store, for arguments sake, are assuming you are running the steam client ontop of MS windows, so with a deck, it’s important to check the compatability/verified by steam status for use on the steam deck.
Forza horizon 5 for example, wasn’t verified for use on the deck, last I checked… you can get it to work, but it’s not guarenteed to be glitch free, or even work at all.