I have previously done an early secdir review on this draft:
https://datatracker.ietf.org/doc/review-ietf-mls-architecture-09-secdir-early-nir-2022-10-08/

For the most part, I stand by what I wrote then.  The document is very well written and provides a thorough analysis of security and privacy. It is now section 8 rather than 7.

As for the nits:
* "MLSCiphertext" has been renamed to "PrivateMessage".  It is still used without having previously been defined within the document. Still only a nit because it is defined in RFC 9420.
* Section 7.2.3 (now 8.2.3) still defines "deniability" only to assert that MLS "does not make any claims with regard to deniability", which is still strange.
* The superlative language ("extremely", "very") has been toned down. Thanks, although I still think that "clients have the extremely important role" is a strange way of saying SHOULD.