I have tested all the other programs I use on a dialy basis, along with other browsers like chrome and edge, and have concluded that it cannot be a windows issue as it is only Firefox that does this. When using the windows snap resize feature if firefox does not get resized to fit the entire screen then the side of the browser which is next to the other monitor will overflow into that monitor. The result is a couple pixels which span the entire side of the other monitor which is extremely annoying. It is hard to post a screenshot of the issue so I will attach a photo from my phone which should make the issue pretty visible. Just to clarify. This issue only happens when snapping to half the monitor for example; having firefox and discord taking up half the monitor each. If I make firefox snap to fullscreen the bleed/overflow does not happen. I had this issue on windows 10 but after upgrading to windows 11 I thought it might fix itself but unfortunately I think it is firefox causing this.