Games don't appear to recognise refresh rate set using Gamescope in latest versions of Proton

[Wartybix]

Games, when running Proton Experimental, don't respond to the value set using the -r flag. It seems that when using Gamescope with the latest Proton versions, games assume a monitor refresh rate of 60 Hz (even when using higher refresh rate monitors, and when passing such values with the -r flag). With Proton Experimental, the framerate is locked to 60 FPS in games using gamescope when Vsync is enabled, regardless of any value set with the -r flag. However, in Proton 9.0-2 (and on native Linux), games are locked to the value specified with gamescope's -r argument when using Vsync, as expected. Games running with Proton Experimental without using gamescope at all also correctly locks to the monitor's refresh rate.

My Testing

gamescope -e -W 2560 -H 1440 -r 165 -f --force-grab-cursor -- mangohud --dlsym %command%

Using these same launch arguments for the same game, enabling Vsync when running the game on Proton Experimental locks the framerate to 60 FPS, while doing the same running on Proton 9.0-2 (and native Linux builds) locks the framerate to 165 FPS.

I have reproduced this issue on two machines running Fedora Linux 40.

[Wartybix]

I've found that this bug isn't present on Arch Linux. I think this may be because Arch Linux's version of gamescope is more up to date than Fedora's, so I assume it works better with the latest Proton versions.