I saw a graph somewhere that vast majority of income from OnlyFans is earned by a small number of top performers. I assume that something similar happens in the furry community.
Not really. Onlyfans creators are selling the same content to lots of people, while furry artists are selling their time slots for custom art. The top artists can charge more for their time, but there is still a limit to how many pieces of work they can put out each week so the money is pretty well spread down to the less popular artists who are more readily available to take on work.