ECH stands for Encrypted Client Hello. It is a protocol extension in the context of Transport Layer Security (TLS). ECH encrypts part of the handshake and masks the Server Name Indication (SNI) that is used to negotiate a TLS session. This means that whenever a user visits a website on Cloudflare that has ECH enabled, intermediaries will be able to see that you are visiting a website on Cloudflare, but they will not be able to determine which one.| Cloudflare Docs
We're excited to announce a contribution to improving privacy for everyone on the Internet. Encrypted Client Hello, a new standard that prevents networks from snooping on which websites a user is visiting, is now available on all Cloudflare plans.| The Cloudflare Blog