Seems to be a bug, I think it happens most frequently when trying to subscribe to a community on a busy instance. It doesn't seem to affect functionality though, I see new posts, vote and comment, etc. Sometimes if you refresh the page or try again it goes away and says subscribed, but I wouldn't worry, doesn't seem to change anything right now. Just assume it means subscribed. I think for this community right now it says "sub pending" for me actually.
Pretty sure it’s a bug. Some of the smaller instances I’ve subscribed to show “subscribed” right away. The larger instances seem to show pending, but as far as I can tell it works as expected.
probably the creator of the community want to select who can enter and who cannot, it's like for private Instagram profile, the owner have to accept your request
There's no such option on Lemmy at the moment.
It can mean two things:
A) the instance is overloaded, which happens frequently with lemmy.ml
B) the instance has defederated from your home instance
Sorry but that's wrong. The "subscribe pending" thing is just a known bug currently. It means you're actually subscribed but the server on one end hasn't acknowledge it yet due to load.
You can test it out yourself, "subscribe pending" communities show up in your "Subscribed" feed.