I’m sure this has been covered already but just incase …
The new modern plex agents uses a consolidated metadata approach. There is (currently) no way to configure the modern agent/scanner to pull metadata from a single source. All the matching does is match against this consolidated metadata in the plex backend. This metadata can come from the imdb, tmdb and/or tvdb including combinations from all three.
Take the Harry Potter movies as an example. For UK, the titles/summaries come from imdb, cast credits comes tmdb and genre comes from all three 
Feel free to vote [Feature Request] Ability to specify Metadata from a single source (IMDB, TMDB or TVDB) if it’s of interest but I’m not hopefully this will ever be implemented.
