As Jack says, Facebook is hopeless for non-members. I wouldn't know if it were up or down from that - at least not on this Android tablet. The only fully visible post currently says "We haven't heard from Max for a while..."

I don't use Reddit except in extremis. Every page I view it covers with a banner 'inviting' me to use the app and I have to click 'Continue in Firefox'.

Mastodon wouldn't be suitable. There could be a #mudcat hashtag (there isn't at the moment AFAICS) but whether you'd see it would depend on your own server I think. Somebody want to try it?

Somebody could post 'Mudcat is back up' messages to rec.music.folk Perhaps I try that next time and see if anyone notices.

The latest post on there says:

Do you have any???? Christmas Songs? [As seen in Songwriters Magazine] Christmas Songs Wanted NOW for the 7th Annual Christmas Songwriting Competition kicks off:
https://www.songwritingmagazine.co.uk/competitions/christmas-songwriting-competition-2022