I don't have any specific details on hand but it's generally known.

The Fediverse is decentralized and technically any instance is free to associate/connect with whoever they like. If you don't like Nazis, asstrolls, or whatever your intolerances are, then you need not link with them. The problem arises when you have people determining you are guilty by association. If you have Right friends then despite your neutral content your Left friends will cut you off for not being intolerant. Thus the Far Left that has taken over Corporate and Social Media has infested the Alternative Media sphere. I suspect there may even be different separate "Deplorable" factions out there as well as various SJWs cliques that don't get along, thus the tribalism may not be quite so black and shite.

It seems to me we need a new similar system where everyone automatically mirrors everything, but filters would hide unwanted things, and there would have to be a checks and balances system to deal with illegal content before or after it gets shared widely - the only censorship required.

A simple search (https://duckduckgo.com/?q=Fediverse+division) reveals a few related things I haven't read but may be interesting:

Mastodon really is crumbling — and it will only get worse
February 2, 2021
https://sporks.space/2021/02/02/mastodon-really-is-crumbling-and-it-will-only-get-worse/

Understanding the growth of the Fediverse through the lens of Mastodon
01 September 2021
https://appliednetsci.springeropen.com/articles/10.1007/s41109-021-00392-5

Misconceptions About Mastodon and the Fediverse
19 September 2019
https://davidwolfpaw.com/misconceptions-about-mastodon-and-the-fediverse/