Same for me on Fedora 31. Authentication via podman doesn't work for container-registry.oracle.com. With docker - works via sudo only. Without sudo I get 

"open /etc/docker/certs.d/container-registry.oracle.com: permission denied" error

_______________________________________________
Podman mailing list -- podman@lists.podman.io
To unsubscribe send an email to podman-leave@lists.podman.io

Is this about the rootless podman not able to read /etc/docker/certs.d?  Can you loosen the permissions on these files?