rootless_storage_path permission error when changed

[xenon-145]

A fresh install of podman on an up to date void linux with root on zfs worked in rootless mode flawlessly.

I copied /usr/share/containers/storage.conf to /etc/containers/storage.conf and only modified rootless_storage_path = "/opt/containers/$USER/containers/storage" which yielded when just running 'podman info' the error message:
"Error: creating runtime static files directory "/opt/containers/user-a/containers/storage/libpod": mkdir /opt/containers/user-a: permission denied".

The permissions are sufficient. No selinux on the system, just apparmor. Manually creating files and directories works.

Even copying the directory tree from $HOME/.local/share/containers where libpod existed to the new location doesn't help. Asking search machines didn't give fitting answers.
May you give any advice?