I used the recommendation from ArlonFX. "To fix it I went into the directory of the game ".local/share/Steam/steamapps/compatdata/1265920/pfx/drive_c/users/steamuser/AppData/Local/LiS/Saved/Config/WindowsNoEditor" and I've opened "GameUserSettings.ini" and modified "sg.ResolutionQuality" from 50 to 100 (that resolved the bad quality/3d rendering of the game), "sg.ViewDistanceQuality" from 0 to 4 and "IsHighResMode" from 0 to 1"

Thanks again! <3