In in-game selection menus (e.g. choosing the logs at the start) the cursor is invisible and menu options tend to flicker, which makes selection harder
I don't own on steam but GOG so I only tested with Lutris. On Proton7.2-2 video sequences were black, which made the game probably unplayable (since it seems about collecting clues). Changing to newest GE build available on Lutris (7-33) fixed this.
Videos not playing
Game doesn't launch with Proton Experimental and GE-Proton7-29, and with Proton 7.0.4 & 6.3.8 game doesn't play video files which prevents progression at certain point in the game. Fixed by forcing Proton-7.0rc6-GE-1 as mentioned in AwesamLinux's report. Didn't try any other versions.
Inaccuracy in mouse input could be related to the way i have screens set up, since others don't say anything i guess it was only an issue on my end.
Proton-7.0rc6-GE-1
With current Proton Experimental the game does not launch (displays a DX11 error message). With regular Proton menu video is missing. The game does not adapt to 16:10 aspect ratio (some text gets misaligned), but that is likely an issue with the game itself.
Works good but no menu background video
Played with Proton 6.3-8
Using proton 5.0.10 - older version of signifier had problems but latest version works flawless until now. Did not try other proton version
Crashes constantly
Randomly crashes all the time, unplayable
Al cerrar la partida a veces la ventana de steam no responde, pero es momentáneo.