Aight I kinda solved it, just posting in case someone else is wondering.
In my case I had closed out of GTA 5 via Alt+F4 and there was a half-dead process still chilling in the background.
GTA or the Rockstar launcher somehow messes with the monitor settings meaning while the process is active.
After I restarted my computer I got distracted and started GTA before testing the faf client so a new process was up again.
Closed both and GTA and the Rockstar launcher and the game started like normal.

TL:DR After youve tried everything the first page of google suggest, make sure to also check for unnecessary processes which could mess with monitor/graphic settings.