SUMMARY
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Specifically, windows with the accept-focus property set to false, and which are inactive, still receive mouse events. More generally, I am unable to use window rules to prevent a window from receiving any mouse events. The overall task I am trying to accomplish is to have a window with transparency overlaid on top of another window (with the "keep above others" window option), and be able to use the lower window without interacting with the semi-transparent window above it. This is useful for cases where there is not much screen real-estate but where you want to do several things at once, e.g. draw from a reference or watch a video while doing something else.

STEPS TO REPRODUCE
1. Set a window rule to force accept-focus to false.
2. Click on the window.

OBSERVED RESULT
The window received a mouse event even though it was not focused.

EXPECTED RESULT
The window did not receive a mouse event.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: NixOS 22.11
KDE Plasma Version: 5.25.5
KDE Frameworks Version: 5.98.0
Qt Version: 5.15.5

ADDITIONAL INFORMATION
I am using Plasma under Wayland. I have confirmed that this happens with native Wayland windows as well as Xwayland windows.

This bug seems related to https://bugs.kde.org/show_bug.cgi?id=283474 - that patch may have made it so that there is no longer a way to prevent a window from receiving click events.