Some or all of the servers you've tried may have them blocked. There's a lot of them that signed the Fedipact promising to do so a while back when they first started talking about doing this.

Or, it may just be that the servers you're searching with/on just haven't properly loaded it yet. I can't currently remember the actual terms for it, because my brain is super-dookie (and I apologize,) so hopefully that makes enough sense 😅

I haven't tried to find it myself, but I've seen other people say they were able to find it from their Mastodon servers, so who knows!

Also it could just be their own bugs or other fuckery, especially since they're only just starting to test it out in the wild. Could be a mix of things ¯\_(ツ)_/¯