I know this seems unnecessarily complicated, but there are good reasons why servers work like this.
Every server is totally independent, to prevent anyone taking over the network.
It would be incredibly expensive to have a record of every post by every person on all other servers, duplicated thousands of times over on every other server.
So, as a compromise, servers only list accounts and posts that they have "noticed". Here's more info about this: https://fedi.tips/which-posts-and-accounts-can-i-see-from-my-server/
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