I always tab out to play?

Hello and although I play games like s4 league and fortnite and all the trimmings. I have 2 monitors and on the left I play. My problem is only when I move my mouse to the right, that it goes to the other screen for a short time and then when I click because it's the same in the games, I'll tab out. So I can play really net. Does anyone know a solution?

Does your mouse also go over if you play the games in full screen mode?

Have fullscreen is still net.

Make sure it is not borderless fullscreen.