Now oc prioritizes Podman's registry credentials over docker credentials: 

Defaults to ${XDG_RUNTIME_DIR}/containers/auth.json, /run/containers/${UID}/auth.json,
    ${XDG_CONFIG_HOME}/containers/auth.json, ${DOCKER_CONFIG}, ~/.docker/config.json, ~/.dockercfg.

For oc-mirror better to same as oc for the registry credentials . 

oc-mirror version 
WARNING: This version information is deprecated and will be replaced with the output from --short. Use --output=yaml|json to get the full version.
Client Version: version.Info{Major:"", Minor:"", GitVersion:"4.16.0-202405110441.p0.g2cb9f07.assembly.stream.el9-2cb9f07", GitCommit:"2cb9f07e5d07f5fa89ad44d65dada3f10cb0d939", GitTreeState:"clean", BuildDate:"2024-05-11T10:32:09Z", GoVersion:"go1.21.9 (Red Hat 1.21.9-1.el9_4) X:strictfipsruntime", Compiler:"gc", Platform:"linux/amd64"}

always

1) set docker registry credentials  not contain the full authentications;
2) podman credentials contain the full auth;
3) run the oc-mirror command 

3) the command faile: 
error: unable to retrieve source image registry.redhat.io/openshift4/ose-kube-rbac-proxy manifest sha256:ac54cb8ff880a935ea3b4b1efc96d35bbf973342c450400d6417d06e59050027: Get "https://registry.redhat.io/v2/openshift4/ose-kube-rbac-proxy/manifests/sha256:ac54cb8ff880a935ea3b4b1efc96d35bbf973342c450400d6417d06e59050027": unauthorized: Please login to the Red Hat Registry using your Customer Portal credentials. Further instructions can be found here: https://access.redhat.com/RegistryAuthentication

oc-mirror should same as oc : prioritizes Podman's registry credentials over docker credentials