/usr/share/kservicetypes5/knotificationplugin.desktop is in libkf5notifications-data 5.28.0-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | [Desktop Entry]
Type=ServiceType
X-KDE-ServiceType=KNotification/NotifyPlugin
|