I've noticed that a regular contact is now only following 4 people, so I wonder if there's a glitch. Either that, or a best buddy has dumped me. Cry cry.

Also, ups and downs are the nature of Medium. Once you reach 1000 you won't be able to see the ups and downs so easily.

They also make follow backs pretty much impossible after a certain stage because your followers are not listed in order of when someone followed you, and notifications don't work.

Medium has regular clean ups of bots. And some people review their follows from time to time.

So don't worry about it. Just read what you enjoy and write what you enjoy, and people interested in your topics will find your posts. Because the whole thing is more topic led now anyway.