Bluesky publishes no follower history at all. There is no growth endpoint, no historical count, and nothing in the protocol that lets you ask what an account had a week ago. The climbing board therefore cannot be reproduced from the public API: it is the difference between our own daily snapshots of the accounts in our Bluesky directory.
It is ranked on percentage growth rather than raw followers gained, and that choice changes the answer completely. A ranking by raw gain returns the same handful of accounts with millions of followers every single week, because a 0.5% week on a two-million account beats a 40% week on a five-thousand account by a factor of five. Percentage growth answers the question people are actually asking, which is who is breaking out.
The 2,000-follower floor is there for the opposite failure. Without it the board would be an endless list of accounts that went from 12 followers to 40, which is a real 233% and tells you nothing.