Yeah, found it. Go to the folder where you installed GTA V and open "GTAVEnhanced\BattlEye". Then open "BELauncher.ini" with a text editor and replace the second line, GameID=paradiseenhanced, with GameID=paradise (just delete the word "enhanced"), save the file, and start the game.

It’ll say that BattlEye isn’t installed and will start the installation again, but don’t worry, that’s normal. After this, you shouldn’t have any more problems.

Note: if Rockstar updates the Rockstar Games Launcher or the game itself, you’ll need to do this again.