HTTPS in any form would not stop Cloudflare from doing what you describe.
Think about it, an encryption system that stops an end-point server from passing decrypted data to somewhere else
is basically impossible. It would mean finding a DRM scheme that actually worked, and we know that's impossible because of the analog hole.
The only way to stop this would be for the end-point server to be unable to decrypt the data ever, but still manipulate it. That's called homonorphic encryption and it's still only theoretical.
Think about it, an encryption system that stops an end-point server from passing decrypted data to somewhere else is basically impossible. It would mean finding a DRM scheme that actually worked, and we know that's impossible because of the analog hole.
The only way to stop this would be for the end-point server to be unable to decrypt the data ever, but still manipulate it. That's called homonorphic encryption and it's still only theoretical.