I found the issue to be the powersettings of windows (gaming mode, etc) to be the cause. I had 2 tools settings them when going into fs 2020, Asus tool and also System Mechanic. Just disabled the one in the last program and i also use the optimised internet settings in System Mechanic to solve the issues of the download speed to be all over the place before (just in fs2020 i couldnt repeat this problem in Steam or any other downloader), this solved the issue and increased my download speed too the max possible speed.
Toke me months to figure out what the cause was, happy to finally found it! Running @ 4K max settings quality mostly fixed at 100 fps with FSR 2, very happy 