one of the annoying features of mastodon ui is that even if you are open to anyone to follow, the system somehow decides that some followers need to be accepted, and there's no notification of such pending follow requests, and because you don't expect them to be there, you never go to have a look, and then there can be people waiting to be able to follow you for god knows how long and they may be thinking what's wrong with them and why don't you accept their follow requests.