Why do I get "Subscribe Pending" on most communities?

It happens when you sub to a community on a different instance than yours. Instances take a long time to talk to each other, therefore, you get 'pending'. I don't think it's a bug.

In my case, the button doesn't even change, but I totally ignore it, then later I see I am actually properly subscribed.

A bit weird, maybe just a UI issue?

The other thing to note with this bug, at least in my experience and what I have seen, even if it shows pending it will still show up in your 'Subscribed' feed. So while visually it is inaccurate, it seems to actually function properly. To be seen if the upgrade to 0.18.1 has any effect.

It's a bug. Just click the button again to unsubscribe, and then click it again to attempt subscribing again. You may have to do this a bunch of times, and may have to leave for an hour/day/whatever and come back. But eventually it will work.

Same thing as everyone else. I find that clicking twice to get it to say pending then leaving it be works. I'm subscribed to the sublemmy even though it says pending, so I ignore it knowing I'm good. The fediverse is still really buggy, especially since they weren't quite ready for the massive migration from reddit. (am refugee myself)