Why can't I see some posts from reddthat?

Trying to better understand how federation works - from reddthat, I can't see the pine tree and Siberian hogweed posts in the screenshot. Both those users are from instances that we're federated with.

Is it time based? I only joined that community today, and those posts are from days ago.

Edit: some hours later, I can now see those posts posts from this instance 🥳