There is already a total count of up- and downvotes, but please never add karma to Lemmy. We don’t want to deal with karma farmers and minimal karma requirements to post. I don’t care about the moderation issues because karma brought more harm than good. Please never add that bloody dreadful thing to Lemmy. I already saw a bunch of people supporting adding karma to Lemmy, which will turn Lemmy into a cheap Reddit clone and karma-farming hell. Please, never add karma to Lemmy. I beg you. No more karma hell.
Jerboa doesn’t have anything to do with it, it is the app you use to access the fediverse/lemmy.
Lemmy has upvotes, downvotes and the tally of those two. Karma is a step further; on reddit, every user has a total tally (Karma) as well, where all up/downvotes of every comment and post are added together as a “score” for the user. So people post popular stuff to get upvotes and thus have a higher score (which some subreddits required to post).