I wonder sometimes if the numbers are wrong. For example a server I host is up quite a bit in user count and posts, but according to the site the numbers are down considerably. It's strange but it's only a less than 20ish users setup. Plus not all federated services act the same.
Some have sub/supersets of the protocol implemented. For example, bookwyrms way of working with posts are wildly different than mastodon and hashtags will work one way and not the other.
I think it ultimately means that number may not be as accurate for a while while all these different servers figure out what it means to be federated.