Any package I post a release notice for in the News category here is for Virtualmin users and is in the Virtualmin repos. Webmin releases in the Webmin repos are announced on the Webmin website and Github, and are never announced here. Sometimes I announce things that are only in some repos, e.g. OS-specific updates, in which case I will say so.
Virtualmin users only need to follow this category to know everything you need to know about the current versions for Virtualmin systems. If you see it here, it means it’s in Virtualmin repos and you should upgrade to it when it is convenient (unless it is a security release, in which case, you should upgrade as soon as possible…security updates are labeled as such, though I don’t call out minor XSS issues, etc. since those are often not actually exploitable in any reasonable fashion; most reported CVEs about Webmin are for things you’d need a root-level account to accomplish, who already has root, so…).
If you aren’t seeing the packages in Software Updates on your Virtualmin systems, that means either I made a mistake (entirely possible, there’s a lot of moving parts) or your system isn’t configured to get updates from a current Virtualmin repo (/vm/6 or /vm/7 repos are currently maintained).