mount idmap container create failed

[keturn]

How is idmapping for mounts supposed to work?

$ podman --runtime=/bin/runc run -it --rm -v "$HOME":'/mnt/shared:idmap=uids=1000-1000-1;gids=1000-1000-1' \
    docker.io/busybox:stable ls -l /mnt/shared
Error: container create failed (no logs from conmon): conmon bytes "": readObjectStart: expect { or n, but found , error found in #0 byte of ...||..., bigger context ...||...

podman 5.4.1, runc 1.2.5, Ubuntu host

[keturn]

apparently it requires root: containers/podman#25106