In addition to podman unshare (which you would just prefix in front of commands like chmod), you can just temporarily do podman unshare chown -R root: <path> if you backup while the container is down. Don’t try that command on live containers.

For a more permanent solution, you can investigate which user is the default in the container and add the option –user-ns=“keep-id:uid=$UID. This does not work with all images, especially those that use multiple users per container, but if it works, the bind mount will have the same owner as the host.