I have three issues with that design: 1) privacy, 2) Apple banning your iCloud account for some reason without recourse, 3) and this further gives BigTech more control to wall off part of the web.
And it looks like they went and did this with CloudFlare and Fastly without requests for comments like most web standards?
https://www.ietf.org/archive/id/draft-private-access-tokens-...