I've been trying to downgrade my version of GTA V, which is from the Epic store, but can find a way to do it so i would appreciate any help. Thanks.

Current problem with downgrading is that you don't have an actual activation code for the game when buying it through the Epic Games Store. However when using an older patch you have to use an older social club version which requires this activation code. When launching the game on Patch 1.27 through the epic games launcher the game either crashes or when you remove the file responsible for automatic verifying you are once again stuck at having to enter the code.

Ok, so I have to buy the game from Rockstar or Steam?

rockstar , if you want to use autopatcher