URL got turned into unblock.federalregister.gov – how?

So I went to make a post on https://www.federalregister.gov/documents/2022/09/21/2022-20470/americans-with-disabilities-act-accessibility-guidelines-for-buildings-and-facilities-architectural

Americans With Disabilities Act Accessibility Guidelines for Buildings and Facilities; Architectural Barriers Act Accessibility Guidelines; Self-Service Transaction Machines and Self-Service Kiosks

which is taking comments right now. And then I looked at it just a few minutes ago and it said it was a Dupe! I was surprised because it was pretty new. So then I looked at the url and it was https://unblock.federalregister.gov/ I really doubt I put that url in so? Does HN rewrite some urls we enter based on redirects from site? Just wondering, but it seems... weird.