I'm pretty sure they don't block coinjoins, but I'd have to verify that. I seem to remember seeing conjoins on my knots node before.
Discussion
Maybe they did in the past
nostr:note1pmhegd83hm3c2p3mfyhq84f7t78mm379ah6a0zh056rq0lfpcf5qq6vrpl
This definitely deserves an explanation and some digging.
