MarsSeed [1] filed a deletion request for libksysguard-light [2]: As former maintainer remarks in last comment:
"Note this package is no longer needed, as libksysguard > 6 no longer depends on webengine (or webchannel)." From now on users shall migrate back to extra repo's libksysguard. [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/libksysguard-light/