1 - Proton experimental is a moving target and is rapidly evolving.
2 - What exactly is your GPU, and maybe tell us your pc specs (even if it’s just through the info tab in the settings menu) (also put it in your post for others)
3 - that sometimes happens to me when using gnome-software (which Ubuntu uses? or something really similar?), I usually just surrender and use the terminal, not like I install more than 1 thing in a normal month anyway.
4 - if the issue is with proton, then other games wouldn’t work. (try running a very light, single player game to test proton, many F2P games under 20 mbs exist on Steam)