Suzerain (1207650) freezes and has bad graphics with Proton

**Game information**
Suzerain (1207650)

**Distribution name and version where applicable**
Pop!_OS 22.04 LTS

**Flatpak info**
Flatpak 1.14.6
default, host gl-drivers

**Problem description**
The game freezes and has oversaturated visuals compared to when I play it on Windows compared to Proton with Flat Steam.

**Does this issue reproduce with native Steam**
No. I previously said I had an error with native Steam, but closing and reopening fixed it.

The report names no project file, test, or entry point. Start by reproducing Suzerain (1207650) through Flat Steam with Proton on Pop!_OS 22.04, then compare it with native Steam; done means the freeze and oversaturated visuals are reproduced and their source is narrowed to the reported environment.

Written by the indexing model from the issue text.