It’s more that every sub had much different levels of activity so one repost would get attention while another dwindled.
The issue with Lemmy is activity is not centralized so each individual repost sees roughly as much activity as the other, so as far as sorting goes, they’re all considered to be as equally active, i.e. “Hot”. It’s all kind of flat line across communities.
We just need more activity, more people, more voting, making making more posts.