Sims 4 is free, and there's a DLC unlocker that lets you get all the DLCs in your legit copy. You might have better success installing the EA app in Proton/wine, logging in a throwaway account, and then installing the official base game.

I also recommend Lutris instead of Steam for non-Steam games, I've found it easier to work with and it can also automatically add links back to Steam if you like having all your game in one place.

FitGirl often repacks DODI and other repacks to make them smaller. I've heard people having trouble with FitGirl repacks often have a better time with the DODI ones.

Check the site to see which source was used to make the repack and try downloading the source one instead if that's an option. Might solve the issue.

I’ve had similar experiences recently with the game, tried Anadius repack instead and the result was the same, ended up finding the sims 4 updater, which solved all my issues.

Never downloading a full repack again, just use the sims 4 updater.