Valve announced that Proton 9.0 is now available for testing, with lots of game compatibility improvements for Steam Deck and Desktop Linux thanks to it now being based on the recent Wine 9.0 release.
Important to note that major version changes of proton usually break a lot of games, so try the beta at your own risk.
Improved support for input devices with 8+ axes.
This must be a custom controller for lumberjack simulator.
HOTAS setups can have quite a few axes. I have one with I think ten?