This is a ‘just curious’ question:
What is com.plexapp.dlna.db used for?
Its located in: Plex Media Server/Plug-in Support/Databases, and its the only db file in that directory that is old (mine is dated May 26, 2022)
It stores parameters about DLNA devices in your network.
Basically everything you put in “DLNA client preferences” and also settings you make by selecting certain virtual folders in any DLNA client.
If you have disabled the DLNA portion of Plex or you don’t use DLNA clients, you can delete it. It will be recreated automatically.
Thanks. I do recall that I once enabled DLNA, but I later disabled it.