
Maximized Firefox window extends slightly into the display above it.
When I Maximize Firefox, the top bar of the window extends a few pixels to the screen directly above the screen with Firefox displayed.
The same problem happens on both my PCs. It doesn't happen with any other programs, only Firefox.
I've uploaded two example images. In both cases Firefox is on the lower screen. The windows taskbar is at the bottom of the top screen. When the Firefox window isn't maximised the window doesn't spill over into the next screen. When Firefox is maximised, a grey strip of pixels can be seen spilling over into the next screen.
Running:
Firefox 91.0.2 (64-bit)
Windows 10 21H1 19043.1165
DPI scaling 100% on both monitors.