I think Valve is really gonna have to put their foot down on publishers.
PC games shipping updates that break the game or make it unplayable on some software configs is kinda ok since thats the nature of PC gaming but they are in the console market now
You can't sell a game that works on a console and then the game be updated to not work on your console after people already bought it.
It's ok if the game doesn't support Steam Deck outright, but publishers shouldn't be allowed to ship updates that break support if it's already supported.