I think you’re confusing how CloudFlare can hide the server IP from the user (to protect against DDoS) versus how CloudFlare DNS hides the client’s IP from the

I think you’re confusing how CloudFlare can hide the server IP from the user (to protect against DDoS) versus how CloudFlare DNS hides the client’s IP from the name server, even though the Client IP is exposed to the web server by Cloudflare, and of course standard Cloudflare is irrelevant if the requested site isn’t using the Cloudflare service in the first place.