I used protontricks to install the baldurs gate 3 mod manager (BG3MM) and add mods to the game. It works flawlesly but there is a little thing. I have to lauch the BG3MM with protontricks, install the mods and export the list to the game. Then if I launch the game from BG3MM the game will perfom not so good, especialy on dialoge scenes. So what I did was to, export the list as ususal and then close BG3MM and launch the game from steam like normal. Now the game runs as good (or a little better) as it did on windows. This is the guide I used to do everything: https://www.reddit.com/r/BaldursGate3/comments/1lrme8n/guide_modding_baldurs_gate_3_final_patch_on_arch/

I had been playing for at least 20hs in linux and it runs like it ran in windows.