Not really, you probably can already see the posts on your frontpage feed (which is exclusive for your subscribed communities) and it also already should appear on your subscribed list.
And as the other user said, it is a bug that it appears as pending. At least on desktop when it days that I reload the page and press the subscribe button twice and it fixes, alternatively on the app “connect for lemmy” I have never seen the issue. But regardless it’s not really a problem