If it helps, I have a negative reputation at the moment as well and couldn't figure out why. My understanding is:
"downvotes", which are called "reduces" on kbin, contribute negatively to your reputation score.
"upvotes", which called "favorites", do not contribute to your reputation score in either direction.
"boosts", which are similar to Twitter's retweet feature, are what contribute positively to your reputation score. When your comment/post/thread is "boosted" by another user, it shows up in the microblog/mastodon feeds of people following that user.
Maybe someone else more familiar with kbin and the fediverse can correct anything I have wrong.
This system seems inherently flawed, is there a breakdown somewhere why this was the design decision?
If this site acts anything like reddit, people will at a point jump in the downvote train and will be "unfairly" downvoted en masse. If the upvote button next to the downvote doesn't offset that I expect we'll see a lot of negative reputation.
Maybe it's a technical hurdle or something -- and it's not like it's that important anyway -- but kinda seems just strange to me.
There was no design decision. Kbin was not ready for prime time and Ernest has said as much. Everything was slapped together and will take time to sort out.
The reputations system is still a bit messed up and still works like in th earlier days when upvotes were actually boosts. It's probably gonna get changed eventually.