It seems to me that the simplest explanation is that kbin handles additional actions, such as user content boosting, and the AP structure is also slightly different. While Lemmy <-> Lemmy cooperate well with each other, kbin can cause confusion through erroneous server queries, significantly increasing the load. I have been working on reducing unnecessary requests, which was a result of migrating to a new server and discovering weak points. Work in this area will be continued to ensure that we do not harm each other primarily.