Thanks.
Your Bugzilla reference triggered me to something I was looking for: a build tag (opensuse/leap:15.6.5.634). I’m sure I will find the repository somewhere (not Dockerhub which updates 15.6 tag every once in a while.)
In case other people were as lazy as I was, in using images from DockerHub…
I replaced “opensuse/leap:15.6” with a reference to opensuse registry, something like “registry.opensuse.org/opensuse/leap:15.6.5.634” to get a stable build.