It’s not really gaming the algorithm. There’s no karma here, no one buying high-karma accounts for advertising, and no one chasing attention when the maximum attention a Lemmy post gets isn’t very much because there aren’t very many users, so there’s no point trying to artificially boost engagement. People are just posting things when they’re online and not posting things when they’re offline, and there are few enough users that it doesn’t take many to create a pattern, and it sounds like you just happen to check at a similar cadence to a few anime fans, so keep seeing things right after they’ve browsed and upvoted what they like. I just checked the All Communities Hot feed on lemmy.world with no communities blocked, and only see one anime-related post in the first five pages, so they’re clearly not constantly at the top. Considering the demographics that would typically use Lemmy, that’s a really low number.