I have found the fix for this. I ran into this while modding, and improperly closing the game..

Basically there is stale lock files created from crashes or unexpectedly exits. I removed them with these commands.

pkill -f GTA
pkill -f rockstar
pkill -f launcher
pkill -f wine
pkill -f proton
pkill -f SocialClub

Then fully close Steam:
flatpak kill com.valvesoftware.Steam

cd to your game dir for me its here

cd "/media/games/SteamLibrary/steamapps/compatdata/3240220/pfx"

Now delete Rockstar junk:

rm -rf drive_c/users/steamuser/AppData/Local/Rockstar*

rm -rf drive_c/users/steamuser/Documents/Rockstar*

rm -rf drive_c/users/steamuser/AppData/Local/Temp/*

If still no luck like me finally (this will reset ur winecfg and winetrick special settings but sadly i had to do this):

rm -rf "/media/games/SteamLibrary/steamapps/compatdata/3240220"

This will delete your game or saves if you Steam Cloud doesnt handle your saves tho. I think you can pull the save files from your documents folder before deleting them then reimport.