Lemmy’s karma system is severely gimped because a user’s karma is different on each server. You can have a million upvotes on .ml and still end up with a karma score of 0 on .world. The only reliable way to detect karma is to query the user’s original server and that can easily be faked by an instance admin.
Kbin has a reputation score that’s actually visible in the frontend but it doesn’t split out post/comment score.