Diagonal line when brightness set lower than 100%

[TheOtterBear]

I just got a new PC and this is one of my must-have extensions for Firefox, but for some reason on my new PC when the extension is active I'm getting a diagonal line from the bottom right corner of the browser window. It's mainly only visible on pages with a white or light background, like the Google search page but not the Firefox extension page, but I do see it sometimes on dark pages, with a gray background, it's just hard to notice. The line goes away if I turn off the brightness back to 100% and begins to show when it's anything less becoming darker/more pronounced the lower you turn the down the brightness.

I didn't have this issue on my old PC. I've tried removing and reinstalling the extension and have made sure my graphic drivers are up to date but the line persists. I'm using Firefox 121.

Edit: I forgot to mention the line persists when I resize the window though it's angle will change depending on the window size, sometime being more vertical. It goes away completely when you maximize the window, but I rarely use it maximized on my my ultra-wide monitor.