My iPad has black borders with the camera. This only happens with the video options (time lapse, slow mo, video) It happens with Landscape and portrait, and its not when I upload them, its on the actual video apps.
The first one is a picture with my actual camera, nd the second is what I see with my videos.
I don't know. Also, the layout on my iPad Pro is slightly different from what is in your screenshot. I am running the 6th Dev beta of iOS 10.3. Anyway, I don't have borders in any of the options with the exception of "square". Have you tried rebooting your iPad?