There are a number of issues with this document.

1. Introduction

"This document updates [RFC6487] with clarifications for RP implementers."

This is not a 'clarification' to the specification of CRL Number Extensions and Manifests, but a revision of the intended role of these two elements of the RPKI system. I suggest dropping the text "with clarifications for RP implementers" 

1.2 Related Work.

It would be appropriate to also reference RFC 6486 (Manifests for the Resource Public Key Infrastructure (RPKI)) in the list of Related work.

4. Security Considerations

This section contains the text: "This document clarifies that, in the RPKI, there is exactly one CRL appropriate and relevant for determining the revocation status of a given resource certificate.  It is the unique CRL object that is simultaneously:

   *  the target of the certificate's CRL Distribution Points extension,
      and

   *  listed in the issuing CA's current Manifest FileList and has
      matching hash (see Section 4.2.1 of [RFC9286])."
      
This does not appear to be a "Security Consideration. It is a commentary on the intended 
outcome when the changes to RFC6487 as listed in Section 2 are applied. This text should be inserted between current sections 1 and 2 as a new section 2, as it as informative description of the intent of the proposed changes.

In addition, there appears to be an implication that an RPKI certificate cannot be validated without recourse to the current manifest for the certificate's issuer to establish the current CRL to be used. This is an important consideration and should be explicitly noted in the document.

It also appears that this document contains a critical update to the certificate validation description of Section 7.2 of RFC 6487. This document should note that it updates RFC6487 Section 7.2, Step 5 and provide an updated wording of this step.