The plugin name is User Tags again.
It had been changed to User Tags Lib to claim a wordpress.org permalink — the directory derives the permalink from the plugin name, once and permanently. The library is not being listed there separately, so the name was buying nothing, and the header justified itself with a reason that no longer applied.
The text domain stays user-tags-lib. That one is not about the directory: user-tags belongs to an unrelated plugin, and two plugins loading translations under a single domain on the same site surfaces as somebody else's strings appearing in these screens.