> It would be quite unfortunate to end up with a UUID v7 in PostgreSQL that’s not quite the standardized one because the patch got merged too quickly.

The chances of that seem extremely low at this point. The contents of a version 7 UUID have not changed since work started on RFC 4122 bis in October 2022: https://author-tools.ietf.org/iddiff?url1=draft-ietf-uuidrev...