When I visit kbin.social, I see new posts regularly. On other servers posts stay on the frontpage for multiple days. This is also true if I switch their sorting to “hot”. So that is probably not the difference.
What is kbin.social doing differently?
Unknown about kbin, but I’ve heard that Hot is currently broken for (most?) instances across the lemmyverse. (This might be related to the size of the instance - apparently for small (single-to-double-digit users) instances Hot works fine?)
Edit: and this is supposed to be fixed in the next release, 0.18