you can’t really fetch follower count on the nostr protocol. its a centralized concept. damus does its best, but relays have limits to the amount of data it can do in a single query.

nostrdb should be able to improve this but it will still be tricky and require lots of data storage because contact lists are changing all the time, not to mention people can spam fake contact lists , why is probably why it says I have 1 million followers which is definitely fake/wrong.