Yeah Lemmy, besides news and technology, is very quiet and I think it suffers from having communities fractured between instances, so niche interests get even less traffic than they would on Reddit. But my Mastodon feed is always busy and interesting. If it isn’t you’re not following the right people yet. I recommend some hashtag searches for things you’re interested in.
Most large instances have a support community. That seems like the suitable place to raise a moderation issue with specific a community on the instance.