Hey , it is definitely Software (driver) related issue. I have had this before in BFA and the only fix was rolling back the graphics driver to an earlier version (20.4.2) , however if I fiddled too much with the general settings I would experience stuttering and black screens, therefore I could never fully utilize the full power of my GPU. I believe it is some conflict between the AMD drivers and Blizzard in-game “recommended” settings. It is strange that it let you through without the notice I got prompted straight away and still get the notice if I log in.