It is because the apt-xapian-index package dropped its dbus servive, which muon used to update that database.
Note: muon is now not actively maintained by KDE, so being dropped in debian/kubuntu.
It is because the apt-xapian-index package dropped its dbus servive, which muon used to update that database.
Note: muon is now not actively maintained by KDE, so being dropped in debian/kubuntu.