TLDR: 3 people working together can gatekeep content on the "active" and "hot" feeds on smaller servers/communities.
After some playing around, I noticed posts disappear after reaching a threshold. A quick search later and I'm in the Lemmy docs reading about how this all works.
In plain English, any three people working together (or one person with three accounts) can stop posts from appearing on the default feed. Once a post reaches -2 it will only appear to people who browse "new." Edit: Of course, it reappears after it climbs above -2, but it's a race against the clock.
As a smaller server, we're vulnerable to this. But we also have some extra mitigations - namely, @seahorse@midwest.social has to approve everyone who joins, and that might weed out bad actors.
So what can you do? Upvote content liberally, downvote sparingly.
I've been trying to upvote nearly everything to try and help with engagement. As others have mentioned, at this point I mainly downvote hateful content or misinformation.