This article goes into a lot of detail, more than is really needed to get the point across. Much of that could have been moved to an appendix? But it's a great metaphor. Someone should write a user-friendly file browser for PDS's so you can see it for yourself.

I'll add that, like a web server that's just serving up static files, a Bluesky PDS is a public filesystem. Furthermore it's designed to be replicated, like a Git repo. Replicating the data is an inherent part of how Bluesky works. Replication is out of your control. On the bright side, it's an automatic backup.

So, much like with a public git repo, you should be comfortable with the fact that anything you put there is public and will get indexed. Random people could find it in a search. Inevitably, AI will train on it. I believe you can delete stuff from your own PDS but it's effectively on your permanent record. That's just part of the deal.

So, try not to put anything there that you'll regret. The best you could do is pick an alias not associated with your real name and try to use good opsec, but that's perilous.