The document (which obsoletes RFC3901) clearly and thoroughly describes the problems and recommendations.

"Obsoletes 3901" is marked in the document heading and the abstract.
The diffs from RFC3901 are described in a dedicated appendix.

The reference to RFC2460, which was flagged by idnits as obsolete, seems entirely intentional as it aims to provide a historical perspective.
All the other refs look good.

The IANA section provides only a brief overview of the intended IANA action, which seemed a bit light to me.
I was expecting a specific editorial change request, but likely I just don't understand the division of responsibilities here.

I have made a few editorial suggestions that the editors are free to ignore in a PR [1].

All thinsg considered, I beviele the document is ready from an ARTART perspective.

[1] https://github.com/ietf-wg-dnsop/draft-ietf-dnsop-3901bis/pull/45