Mouse wont lock on ANY Fullscreen game/application.

I can confirm that the game bar is the issue

If you are on Win 10/11, go under settings and installed apps

search game bar, click on system components

advanced options for game bar

I hit Repair, Reset, and then rebooted.

Problem fixed

I figured out what's causing it. It was Xbox Game Bar which can be opened using Win + G. I'm not sure what Xbox game bar had to do with it but I tried not opening it before launching the game and my issue didn't occur. Thanks for all your help.

None of this worked. The problem is that my mouse won't lock to my screen and it goes to my other monitor. I'm not really sure why its happening.

I'm going to be honest, I had this problem since october 16 or something to that effect. I did a bunch of things and it fixed my problems. I can open Game Bar, and it doesn't break it.

I can try and give you pointers to what I did to fix my issue, but since I didn't do it properly, I don't know which worked. I will order them by what I think most likely fixed my issue.

1- Uninstalling all the monitors I have in my "Device Manager" ( I have a gaming laptop, so I also uninstalled the integrated one). Then I rebooted.
* Saw it on this reddit: https://www.reddit.com/r/buildapc/comments/wpv4fq/new_build_dual_monitors_mouse_wont_stay_locked_to/?rdt=61031

For detailed explanation: Right-click windows button, open Device Manager, go to monitors, right-click and press uninstall. Then reboot so they are automatically added back.

2- Uninstalled and reinstalled Game Bar.
Since this is part of component of windows, you can't uninstall Game Bar normally. You can use this Windows Powershell command (use it at your own risk, I advise researching a little)
Open Terminal or Powershell as administrator
Enter this command:
Get-AppxPackage -Name "*Microsoft.XboxGamingOverlay" | Remove-AppxPackage
Reboot your computer

To reinstall it, either reinstall Xbox App or open Xbox app and a popup opened at the top of xbox app saying to install Game Bar for it to work correctly.
I had a bunch of errors saying I needed an app to open "MS-gamingoverlay" before reinstalling.

I did other bunch of things. Let me know it none of these worked for you as well and I'll try to come up with other things.

Hello there! I am Charity, I'm an Independent Advisor. I'm glad to help you today!

I'm really sorry that this happened to you. Let's try to disable full screen optimizations. Right-click the game’s executable file, go to Properties > Compatibility tab, and check "Disable fullscreen optimizations."

I would also suggest playing the game in borderless instead of exclusive full screen.

I would also suggest trying to press ALT+ENTER within the game to go full screen. If it goes windowed, please press ALT+ENTER again.

Please let me know if this works for you. I'll do my best to respond as soon as possible.

Kind Regards,

Charity

Please note that things might need more than one reply to completely resolve your issue, as it will completely depend on the complexity of the question and the amount of detail that you have provided me.