So i have made through research about this one, and im certain that it has to do with the game itself.
So what happens usually is that when you are in loading screens / menus the game tries to force my refresh rate back to 144, which makes visible brightness changes on the display, i checked from monitor OSD and it does try to force back to 144, despite it being locked to 60 in loading, and 90 in game. No idea why but the game just keeps trying to force it back to non-adaptive refreshrate. Is the adaptive sync not really working in vermintide 2? If anoyne has some workaround I’m all ears as well!