If that protocol is a technical solution to the problem and match our requirements toward privacy, I don't see why it would not be adopted, then: - The TCP header is not encrypted and thus publicly exposes the IP address of the client - I don't see why the Apple Relays would emit that information since that would defeat its purpose of obscuring the original client IP - It looks like it is a custom protocol between two HAProxy Enterprise instances - It seems to be a feature of "HAProxy Enterprise" which sounds like it is not available under an open source license.

We do have direct point of contacts with engineers at Apple, Facebook, Google etc and do collaborate with them on a wide range of technical topics. The foundation has a dedicated team to vandalism, blocking etc https://www.mediawiki.org/wiki/Anti-Harassment_Tools . I forwarded your remark and maybe they can update the wiki page at https://meta.wikimedia.org/wiki/Apple_iCloud_Private_Relay (it is mostly from November 2021 and looks like it might use a refresh).