Here's an interesting one I came across recently. It seems Valve are doing small hotfix releases of Proton, to go along with some of the bigger releases to get them working.
The problem is that each release of Proton needs a fair amount of quality assurance testing by Valve and their partners CodeWeavers. Proton releases are quite a while between, and with the amount of games releasing constantly, they don't always make a new release in time to get them all working on Steam Deck / Linux.
So this is where quick hotfixes come in.
Recently there was a Beta of Street Fighter 6, which Valve developer Pierre-Loup Griffais showed off on Twitter. In the replies, they noted "All the fixes are now deployed on Proton Hotfix and that branch is selected by default for the game for all players.".
This happened again recently with Cyberpunk 2077, with Griffais posting on Twitter "We have just deployed a performance hotfix for Cyberpunk 2077 on the Deck, no update necessary beyond just restarting the device to get it picked up.".
Today we have Gotham Knights releasing, and once again Valve are on top of it. Gene Park from The Washington Post noted on Twitter how it wouldn't run on Steam Deck and Griffais replied "We've just made a couple fixes and backend changes - it should launch if you un-force Proton selection and try again (or force Proton Hotfix).".
Since Valve set it automatically, you don't need to do anything, unless you forced a version of Proton then you need to undo it.
No doubt there will be plenty more of these quick fixes in future, as developers find so many ways to do things differently and break things or use things that the main Proton releases don't yet support. Valve are up against a moving target for Windows compatibility with Proton. Eventually though, Proton hopefully get to a stage where things like this aren't needed.
ICYMI: Proton 7.0-5 is currently in testing to bring more game support to Steam Deck / Linux.