Alt Tab game but (please help)

so I’ve had this issue for a long time, and I’ve been researching into it for months but still have no clues or traces on how to fix it. Basically when I alt tab out or into a game my screen goes black for like 5-6 seconds and then it loads. I know the problem but I just don’t know how to fix it. it’s because my resolution and in-game resolution are different. at first I wasn’t sure but then I ran some tests and confirmed that’s what’s causing my problem, if anyone knows how to fix it please help this bothers me so much.

(I’ve tried turning everything in focus assist off and also my drivers are updated)

The only way to fix it, is if the game offers some kind of “Borderless Window” mode. Switching between a properly fullscreened game and out of it will allways produce what you described. No way around that really.
Some games handle it better than others. Certain games make Discord Audio Lag for a few seconds, others stay up even with proper Fullscreen. As someone who uses 3 Monitors, i can feel your pain. But there is no OS level setting to change that behavior.