I don’t know if this is expected behaviour or a bug, but I lost all my favourite subs too, so you’re not the only one who has been affected.
I was only using the favourites feature because I wanted a way to list all the communities that I’m subscribed to. As far as I’m aware, there isn’t a way to view your subs list yet (though please correct me if I’m wrong).
Oh no, sorry to hear that. Yeah I feel better about only losing my favourites now lol. Have you tried deleting and reinstalling the app?