I’m quite tired at the moment to get really into the weeds on this, but this has been posted on the subreddit (https://www.reddit.com/r/MusicBrainz/comments/1s43fh8/music_genre_tree/) - the series in question is:
I think its misuse of the Series entity type, not entirely sure what they’re aiming to achieve?
Last time we had mega bumper sized series it caused a lot of problems performance wise.
I have requested OP explain what they’re doing