registry.redhat.io/openshift4/ose-operator-registry:v4.5.0 and registry.redhat.io/openshift4/ose-operator-registry:v4.5 both point to the same image digest. I expected v4.5 to track the latest 4.5.z and v4.5.0 to be fixed, with one fixed tag per z-stream. This appears to also be true of v4.4/v4.4.0. Earlier minor version tags match my expectation.
The component versions don't increment in 4.4+ like they did in previous releases (when they did, they weren't reliably accurate, which is why we stopped doing it). Just the release (made up of a timestamp) increases. If you want to pin to a component in a particular release, you have to include the release in the tag e.g. 4.5.1 was registry.redhat.io/openshift4/ose-operator-registry:v4.5.0-202007012112.p0