Mouse goes out of full screen mode?

When I play fortnite in full screen mode and move e.g. B. When aiming to the right, the mouse suddenly switches to the second screen and the game is knocked out, the graphics driver is up to date, the PC has been restarted and disconnected from the power supply and the screens and hardware have also been disconnected and reconnected. The problem has existed since yesterday evening without having changed anything and no, I'm not in the frameless window mode. 😅

How can I solve the problem?

Try using Alt + Tab to switch to window mode and back. This has already helped me several times to remove the taskbar.

Hope this helps you