[Testing Update] 2025-07-15 - Kernels, KDE Frameworks, NetworkManager, Poppler, UMU

[Wollie]

I only can guess, have a look into this:
https://archlinux.org/news/plasma-640-will-need-manual-intervention-if-you-are-on-x11/

[Unstable Update] June 2025

On Plasma 6.4 the wayland session will be the only one installed when the users does not manually specify kwin-x11. With the recent split of kwin into kwin-wayland and kwin-x11, users running the old X11 session needs to manually install plasma-x11-session, or they will not be able to login. Currently pacman is not able to figure out your personal setup, and it wouldn’t be ok to install plasma-x11-session and kwin-x11 for every one using Plasma.