After I SIGTERM’d plasma_wayland firefox-nightly chromium-browser, [1] my Meta and Alt keys became disabled without it active, until I invoked qdbus-qt6 org.kde.Shutdown /Shutdown org.kde.Shutdown.logout. [2] This appears to be reproducible. Why do those keys become bound to the nested compositor?
I’ve since resolved it by using:
#!/usr/bin/env sh
export $(dbus-launch) && \
kwin_wayland
…instead of pwsh -Command kwin_wayland. The documentation did advise that. [1]