I just want to add my two cents. I was playing the Linux (non-Proton) version on the Steam Deck. I ran into a situation where the game keeps crashing right after loading back up. I suspected the issue might be an issue with a mod (no complaints about the game/mod compatibility, I include this just to provide some background).
I changed to Proton (Compatibility mode) and launched the game to see if the problem with the fame crashing persisted. I noticed that the zoom had stopped working as described by OP.
While digging into this I found that Zomboid recognises controller as X-Input in Compatibility mode. In Linux mode the controller is recognised as a Steam Virtual GamePad.
This is probably known by the team, and not sure if it is a fix that needs to be done by Indie Stone or Valve/in Proton. My last question is. Is there a way to change the config files to force the controller to use Steam virtual Gamepad in Proton? I tried to copy the Joypad file from the Linux file directory to the Proton game directories and change the config to point to the correct Joypad file in the ProtonDB version, but no joy. Any tips?
