That is "normal". I've had the same issue before, regarding my contrast. My desktop and all looked like I turned down my screen's brightness to 0 and when I went back in and out again, it was all super bright and flashy.

There are games tempering with contrast, colour profiles and such, it's not common but it happens. If I just could remember one popular game that does it, too, and you can see your screen adjusting when Alt+Tabbing. Sometimes this "adjusting" fails or is skipped and you are stuck with it as long as the program runs.