I work for SIDN, the ccTLD registry for .nl. Around 2022, we came up with an idea together with some of our registrars: to add a "for sale" button to the WHOIS page for domain names that are for sale.

We soon realised that the underlying method could be useful beyond .nl as well. So at SIDN Labs, we decided to turn the idea into an RFC and take it through the IETF process.

https://www.sidnlabs.nl/en/news-and-blogs/a-digital-for-sale...

https://www.sidn.nl/en/forsale-from-a-pilot-scheme-to-a-grow...

Taking it through the IETF was an interesting and very educational experience. There were both supporters and people who challenged various aspects of the proposal, but I think the document ultimately became much better because of that.