Oh, and upon further reading, this draft was deprecated in favor of the "Rate Limited Tokens" extension [1] to the overall “Privacy Pass” draft specification [2] (authors are from Google, Fastly, Apple, Cloudflare)

Submitted for discussion separately at https://news.ycombinator.com/item?id=31852145

[1]: https://datatracker.ietf.org/doc/draft-privacypass-rate-limi...

[2]: https://datatracker.ietf.org/doc/draft-ietf-privacypass-arch...