I haven't found any sources about this, so the following is just my hypothesis based on the information I could find, and what I already knew. My suspicion is that because the OSD chip rein the FC effectively receives a different signal than the camera sent (because of a difference https://waylonkmgzs.bloggosite.com/41090700/immer-meine-osd-課程登錄-um-zu-arbeiten