[ev1]

Doing this if you are intentionally trying to protect or hide your origin is effectively guaranteed killing on the origin. For example, if Cloudflare unproxied one of my subdomains I'd leave them immediately, and likely have to change all my infrastructure and providers due to attacks.

This is also a terrible idea because of ACLs/firewalls only allowing traffic from CDN (this is extremely common for things like Cloudflare and Akamai) and relying on the CDN for access control.