Full screen video player resizing/changing position
When I open a video on Twitch, YouTube,... and put the video on full screen, every time the video gets moved to the right. When I leave the full screen and comes back then the problem doesn't happen any more until I close and re-open Firefox.
I've tried it on my 2560 x 1440 144hz monitor and my 1920 x 1080 60hz, so it isn't due to the resolution of my screen. The problem isn't due to the dual monitor because my screen on the left has the same problem on the same side.
When I opened the Troubleshoot mode the problem was fixed. The extensions I've aren't causing this ( because I've the problem without ) and my theme too because I've none.
I already got this problem a while ago and don't remember how I fixed it. I've putted a screenshot of the top left of my screen.