MarsSeed  filed a deletion request for kdeplasma-wallpaperswitch :
Orphaned package, project discontinued in 2019:
"Unfortunately, due to recent changes in Plasma, WallpaperSwitch no longer works" due to "major architectural changes within Plasma".
There is no point in keeping this package as it doesn't work (incompatible with KDE Plasma Desktop since 2019).
Nothing in AUR depends on it.
 https://aur.archlinux.org/account/MarsSeed/  https://aur.archlinux.org/pkgbase/kdeplasma-wallpaperswitch/