MarsSeed [1] filed a deletion request for plasma5-theme-mcsur-git [2]: Not compatible with current Arch Linux / KDE6.
Also upstream is abandoned for close to 18 months. [a] [a]: https://github.com/yeyushengfan258/McSur-kde [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/plasma5-theme-mcsur-git/
