I think I solved it by going in to NVIDIA control panel and changing some settings.
Edit: So basically I changed the colour settings in the NVIDIA control panel and my monitor in HDR mode. It feels more like a counter fix to the grey filter rather than removing it. It's still there. When I change between HDR mode and any other screen settings (on the monitor settings, using the buttons on the monitor) the grey filter disappear for a split second. So it's still there. I've never seen anything like this before. Games normally take control of the screen settings if I understand it correctly. But it seems Battlefront 2 did something, and there seems to be no fix for it...
Some observations (I will refer to the problem as the "grey filter" because it washes out the screen colors and contrasts:
-ex Minecraft: fullscreen mode=normal colors, windowed view=grey filter
-In games = no grey filter
-Outside games = grey filter, like browser, word, Netflix etc
-Screenshot = no grey filter
-Changing between HDR and no HDR makes the screen normal (in regards of colors) for a split second. Meaning the grey filter is still there on top of everything else.
-Reinstalling display adapters does nothing
-Display Color Calibration does nothing - as if the grey filter has nothing to do with the display
-changing NVIDIA control panel settings might do some counter against the grey filter
-monitor HDR mode might have higher impact than the NVIDIA control panel settings
-before playing star wars battlefront 2 14th of February 2021 caused the grey screen
-playing star wars battlefront 2 previously (far back as over a year ago) didn't cause any grey filter
-my secondary screen connected to the same graphics cards doesn't show the grey filer
-changing the HDMI port on the graphics card did nothing.
Conclusion
-wherever this grey filter is located, it's connected to the screen it happened to.
-The grey filter is on top of everything except when fullscreening a game
-HDR mode is not a fix, it's a counter