And for those wondering, my own self-hosted server was only blocked by one instance, which I've never heard of. It hosts four registered accounts, and seems to block pretty much every other known server.
@thisismissem I believe it was a Misskey server, not sure if that makes a difference.
I'm not too familiar with how this platform handles domain blocks, or how to view them, but that particular server showed up as blocking all the domains I checked (the big ones analyzed in the article, plus mine), so I'm assuming they must be blocking a rather large list.
@stefan@thisismissem yea lol. I looked into that awhile back and came to that conclusion. They haven't posted since February and have automated blocking.