It was me- many kids here seem to attend Chinese school on Saturdays, where I believe writing is part of the curriculum. I don’t know how many of them take AP Chinese, but my kids have several,friends who have.
These tend to be the same kids who do a lot of self-studying for other APs as well. We have one friend who was a National AP scholar (I think that means 10 APs with a score above a certain level, probably 4) as a junior, which is pretty extreme in our school, as they also limit how many classes can be taken (many of hers were self-studied, outside of our curriculum, including chemistry, etc- despite the fact that the classes are offered at the school. Not my ideal schedule, for sure.