This is the security directorate review done on behalf of the Security AD's.  Others should treat this like a regular last-call review.

This document fills in a hole: RFC 7050  reserved the special DNS name "ipv4only.arpa" for determining how a client can find out its local network NAT64 prefix, but did not finish the job by not registering that name in the Special-Use Domain Name registry (SUDN).

I was surprised to see that this was an AD-sponsored document; various AD's may wish to discuss the rationale during IESG review.  The paranoic in me finds it interesting that https://datatracker.ietf.org/doc/draft-cheshire-sudn-ipv4only-dot-arpa/shepherdwriteup/ has no answer to question 9. :)

This is a good document plugging a hole, and explaining the impact on DNS in a variety of configurations.  Ship it.

Sec 3 discusses the intent and why ipv4only.arpa is special. Sec 4 discusses what happens when software doesn't do the implied/required special-casing.  It covers several types of deployments. Sec 5 provides what is missing from RFC 7050, but arguably is "better" because of the experience learned.  There is interaction between DNS64 and DNSSEC that is described in Sec 6. A variety of mechanisms are discussed and a migration path is proposed, ultimately justifying why the zone must be insecure. Sec 8, the SUDN registration section, recapitulates the previous sections without rationale or side-notes: if you read only one setion, read this.