Non-vanilla/mod files require manual removal. Skip the redownload of 100+gb - save a whale, some frogs, your bandwidth, and time (or even space if you are struggling to house 'clean' copies to fix problems). Verifying cache - also does not remove all non-gtav files. Uninstalling and reinstalling gtav - does not always remove non-vanilla/mod files. Here for epic version? Clean folder as mentioned below - verify data using epic launcher.
