Is it that hard to implement? Supporting an additional UUID version in PostgreSQL sounds like the most trivial change to implement (compared to anything that touches core backend, table management, replication, query schedulling, and so on).
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.
EDIT: here is the IETF working group page https://datatracker.ietf.org/wg/uuidrev/about/
Their milestone seems to submit the final proposal by March.
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...
There's clearly little pressure to rush this, considering it's not difficult to add a custom function generating UUIDv7 ...
For me the main challenge was that it's still considered a draft (AFAIK). It may be unlikely to change, but if it does I'd rather not have to deal with persistent UUIDv7 data generated per some previous spec.
Also, if I really want/need UUIDv7, it's not that hard to create an extension that generates UUID in arbitrary ways, including the proposed v7.
there's already well maintained extension https://github.com/fboulnois/pg_uuidv7
It's slightly different from recommendations by draft RFC version (there's no counter), but fully within spec requirements. From practical point there's no difference at all.