While I’m not entirely sure wat it actually means, the message you get on that site right now might be the reason (some kind of experiment gone wrong artificially inflating the numbers):

I was creating an implementation for the activity pub instance service transfer, but it seems to have spread far. We are very sorry to those who have experienced inconvenience.

All temporarily used data has been removed and all data has been removed. The figures in the data will soon converge to zero.

I trawled unintentionally.