See pgmp. It shows 1.0.0 coming before 1.0.0b2, but it should be after 1.0.0b3. That is, it's not sorting as the highest number.
Looks like this is because the old semver domain is deployed to production, rather than the new C type. And since the USING clauses were removed from the source, they no longer sort correctly.
So I'll have to schedule a downtime to switch to the C type.
Fixed yesterday by switching to the C semver type.