The Appendix of Decentralization and erasure: Blacksky, Bluesky, and the ATmosphere is a roundup of various articles and posts on the question of whether or not Bluesky and the ATmosphere are decentralized and/or federated. There are lots of interesting perspectives here, including from @laurenshof on @fediversereport, @cyrus, @cwebber @bnewbold, @rysiek, @jonny, @possibledog, @oblomov, @rwg, and @Kye. Every single one of those posts was worth reading, and I really appreciate the time everybody's put into it.
That said, it's still very strange to me that as far as I can tell none of you mentioned what seems to me an actually-existing example of decentralization on Bluesky today.