No it’s not. File written from inside the container into a mounted volume as root will be owned by root outside the container (uid 0, to be specific; doesn’t matter what the user is named).

Edit: I might have misunderstood parent, who might be referring to Podman attempting to manage the uid mapping.

The parent comment is still talking about rootless podman (and really just user namespaces). Root in the container is absolutely mapped to the user executing podman outside the container.

If it mapped to root outside the container, you could just use podman to create setuid scripts owned by root for very trivial privelege escalation.

Yes I think you are right --- I was mistaken. Docker without the rootless operate in the way I described.

Last thing I remember you can tweak your /etc/setuid, setgid to properly map between the user inside the container and outside