@fastfinge Did you follow @ap.brid.gy from your Bluesky account? If I search for @fastfinge.interfree.ca@bsky.brid.gy here on sfba.social, I don't get any results, and the usual cause for that is if you haven't opted into to the bridge between ActivityPub and bluesky. (The person you mention who is on bluesky could use the same bridge to follow ActivityPub accounts who have opted into the bridge - lots more documentation at fed.brid.gy/docs ).
@fastfinge Hmm, I realize that I don't quite remember most of the details of this process. Your speculation that there could be some kind of cache or other delay, I guess in Bridgy Fed, is an interesting one.