Compatibility Report

• Name of the game with compatibility issues: TumbleSeed
• Steam AppID of the game: 457890

System Information

• GPU: AMD Radeon RX 5600 XT
• Driver/LLVM version: Mesa 21.1.8
• Kernel version: 5.14.18-200.fc34.x86_64
• Link to full system information report as Gist: https://gist.github.com/joshas/4c98ea2d78b4bf498d01b0e23c48e36e
• Proton version: 6.3-8

I confirm:

• [x] that I haven't found an existing compatibility report for this game.
• [x] that I have checked whether there are updates for my system available.

steam-457890.log
TumbleSeed_d3d11.log
TumbleSeed_dxgi.log

Symptoms

When starting game in full screen mode loading screen is frozen, sound is playing. After 10 or so seconds screen updates, but game never starts, and even sound cuts off at some point later.
If Alt+Tab is used to switch to other application and back to game - game starts running at normal speed. After switching to "Activities" view on GNOME by pressing "Super" key game starts running in normal speed while displayed in overview (small window) among other windows.
If fullscreen mode is disabled, game starts without issues. Disabling Steam Overlay doesn't fix the issue.
Using PROTON_USE_WINED3D=1 %command% launch option game starts normally even in full screen mode.

Reproduction

Always.

Some other Unity games also have same issue, e.g. Deepest Sword (1647160).