SUMMARY
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In plasma-wayland: using two monitors with mismatched resolutions (3840x1440@60hz and 2560x1440@144hz), setting the scaling of the higher resolution monitor to a value higher than 100%, while keeping the lower resolution monitor at 100% causes the right-click menu on the smaller resolution monitor to disappear on hover. The individual elements of the menu return when hovered over, but the background remains gone. This only happens for right-click menus on the desktop and on panels. Changing the scale of the lower resolution monitor to any value higher than 100% fixes it, but this causes blurring due to the scaling so this is undesirable. The opposite situation, raising the scale of the lower resolution monitor above 100% while keeping the scale for the higher resolution monitor at 100%, causes the same issue; but still only on the lower resolution monitor (meaning that the menu only disappears on the lower resolution monitor). Changing the frame rate of either monitor has no effect. A clean install of the OS also did not solve the issue.
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STEPS TO REPRODUCE
1. With two monitors with a mismatched resolution, raise the scale of either monitor while keeping the other at 100%.
2. Right-Click on the Desktop
3. Hover over any of the elements in the right-click menu that appears.

OBSERVED RESULT
The right-click menu disappears, except for any elements that have been hovered over.

EXPECTED RESULT
The right-click menu remains

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: EndeavourOS 
(available in About System)
KDE Plasma Version: 5.26.5
KDE Frameworks Version: 5.101.0
Qt Version: 5.15.7

ADDITIONAL INFORMATION
Plasma-Wayland-Session: 5.26.5-1
NVIDIA GPU, driver version: 525.78.01