Fediverse servers work like this: servers only really notice accounts from other servers if someone on your server follows or interacts with them.

The reason servers work like this because of resources. If servers had to keep a copy of every post from millions of users on thousands of Fediverse servers in the world, server running costs would become prohibitively expensive (and most of those posts would probably never be read by anyone on your server anyway).

I'd always wondered this-- the instance I use is fairly small, so most of the time accounts look blank to me when I first viewed them!