What’s the reason for defederating from them? Aren’t they like the original Masto instance? What kind of moderation issues are going on there?

I can help fill in some of the gaps. Mastodon.social is the flagship instance so you get a bunch of people signing up for it, and at times I think some of the reports overwhelm the moderation team. A few weeks ago there was a big issue with spam bots getting through. Some instance owners have a short fuse for this kind of stuff so they opted to defed from it.

Personally, I’m running a small instance so I did not block it. I follow a lot of accounts from there. The spam bots were annoying though.

Spam and bots like other people have said. Then there are the instances that get blocked because of the content and people there. Nazis, racists, trolls, etc. They were coming in from all over during the twitter migration. There was a blocklist on GitHub that was being updated pretty frequently.

There are, but they tend to end up being quickly defederated themselves, because they attract bigots who want to share their bigotry without consequence

there are some, but they tend to quickly become spam and nazi instances. I’m guessing even those ones defederate from the instances that only serve malware though

This is what I want to know. I don’t want to be in a walled garden.