I am the assigned ART-ART reviewer for this draft.

Summary:

This draft to update RFC 8399 is clear on the revisions and is almost ready for publication without major/minor issues. 
However, I found one point of concern, which I comment on below as nits, and I hope you will consider revising them if necessary.

Nits:
In section "3. Security Considerations", RFC 5892 has been updated to RFC 8753 and needs to be corrected.
However, RFC8753 does not describe the algorithm to derive property values or the code points list like RFC5892. 
So, if you want to reflect this suggestion, it would be easier to convey the intention to the reader to write, "This can be done by verifying all code points <https://www.iana.org/assignments/idna-tables> determined by IDNA2008 [RFC8753]."  rather than  "This can be done by validating all code points according to IDNA2008 [RFC5892].".