Updating from Plasma 6.3.5 into Plasma 6.3.91 doesn't remove /usr/share/xsessions/ on Arch, which means there's a broken x11 session option on Arch Linux by default. That crash-inducing folder should be removed in order to avoid crashes and therefore an immense flood of bug reports upon release.
Sorry for not being clear about this: The "/xsessions" folder is what keeps that broken x11 option there.
You're right. We either need to: - make kwin_x11 a mandatory dep of plasma-workspace - change they TryExec line in our .desktop file to kwin?
That's an issue in Arch package https://archlinux.org/packages/kde-unstable/x86_64/plasma-workspace/ Whose dependency include only optionally kwin-x11 but has a file `usr/share/xsessions/plasmax11.desktop` in it. Arch probably need a new plasma-x11-session package or as David suggested.
*** This bug has been marked as a duplicate of bug 504669 ***