This post will show you how to stop the mouse cursor from going off screen in the ROBLOX game. Here are all the effective workarounds you can try.

Log out of all Roblox accounts on all devices where you play the game. For example, on a Windows computer, navigate to the upper right corner of Roblox and click the Logout option.

If KRNL-Injector failed to find the Roblox process, delete KRNL App data and see. If that doesn't help follow the solutions mentioned in this post to resolve the issue.