The game's been randomly crashing until I just couldn't progress anymore past a load. After I switched to 5.0-10 the game didn't crash anymore, and I was able to finish the game, without further crashes.
The last leg of my gameplay was done on 5.0-10 that part didn't crash even once. This version of Proton could be the best one to play the game. Apart from the crashes, the game ran fine on every version of Proton that I tried from 5.0-10 to 7.0-2 and custom versions.
The game runs perfectly fine,
The game seems to crash the most with Proton Experimental, Proton GE custom, and 7.0-2 are more stable, but the game crashes every time as you start mission 3 during the load screen.
While running 6.3-8 the game generated the following crash log: UnityPlayer.dll caused an Access Violation (0xc0000005) in module UnityPlayer.dll at 0023:105bc690. 64% memory in use. 0 MB physical memory [0 MB free]. 0 MB paging file [2048 MB free]. 0 MB user address space [0 MB free]. Write to location 00c00000 caused an access violation.
I managed to load that mission successfully using Proton 5.13-6.
Unfortunately 5.13-6 isn't a silver bullet, because when the guship hit Nora, she fell under the hoverbike, and that borked the game. I couldn't get back to the main menu to reload the checkpoint.
Cannot progress past a certain loading screen without crashing
Performance seems lower than normal
Game crashes several times a mission, requiring you to replay the same areas over and over. One particular loading screen always crashes, making the game not completeable
RADV_PERFTEST=aco gamemoderun
Occasional texture flicker
Sometimes crashed when loading a cinematic or loading a new area
In the game's forums, people frequently complained about performance & optimization. I had no issues holding 60fps at 3440x1440, with everything maxed but Ambient Occlusion turned off.