A couple of ideas: Are there other teachers who teach the AP English classes? could you talk to them? could you share your concerns with school admin? It might be hard for them to hear this, but you do have a small point.
something about low AP scores that we’ve seen at our HS (where very few kids go somewhere besides state schools/cc); So many AP classes are offered as dual enrollment classes; you get the college credit. Those classes mandate that kids take AP tests, yet the grade in the class and college credit trumps AP scores. So - the kids work hard for that grade; and can care less about the AP test.