Some parts of the game (like when controlling a turret) cause VERY loud static to be outputted. The noise is so loud, that even when setting the volume to the lowest level (not muted) the noise still feels like it's 100x louder than max volume. This audio is NOT present when playing on Windows, which seems to indicate it's an issue exclusive to Proton. I don't recommend playing this game through Proton for this alone, as it could easily damage your hearing, let alone your speakers/headphones.

The game isn't optimised very well and runs on a single core so there is some stuttering. This isn't a fault of Proton however -- just how the game was designed.

Sometimes the game can crash or hang when at loading screens when using the Visible Upgrade mod's multicore mode (you are warned about this in the mod's configuration tool).