Disappearing followers almost certainly are those who quit Medium. The likelihood that followers who follow dozens each day then return to see if you followed them back is zero.

Disappearing subscribers may be different. But may I kindly suggest, even if it is "about your writing," that's not to say that your writing needs to be other than what it is. There's a lot to read out here, and everyone chooses what speaks most to them. We write for those to whom our words mean something. If our goal is to say exactly what we need to say as clearly and beautifully as we can, then the extent of our reach is not quite so important.

(And if our goal is to make money from writing, I suspect Medium is not the right place!)

All best, Christine.