ErrImagePull Error with a message authenticationrequired

Elasticsearch operator is installed on Openshift. While creating the elasticsearch cluster, below error is seen:

Normal Pulling 5s (x2 over 27s) kubelet Pulling image "docker.elastic.co/elasticsearch/elasticsearch-ubi:8.12.1"
Warning Failed 4s (x2 over 26s) kubelet Failed to pull image "docker.elastic.co/elasticsearch/elasticsearch-ubi:8.12.1": Get "https://docker-auth.elastic.co/auth?scope=repository%3Aelasticsearch%2Felasticsearch-ubi%3Apull&service=token-service": authenticationrequired
Warning Failed 4s (x2 over 26s) kubelet Error: ErrImagePull

One observation to share: OpenShift cluster is behind the proxy and env variables HTTP_PROXY, HTTPS_PROXY, NO_PROXY are specified for podTemplate.spec. Still the above error is seen.