You created a Kubernetes deployment by running kubectl run nginx image=nginx labels=app=prod.

This command correctly lists pods that have the label app=prod. When creating the deployment, we used the label app=prod so listing pods that have this label retrieve the pods belonging to nginx deployments. You can list pods by using Kubernetes CLI  kubectl get pods.

Ref: https://kubernetes.io/docs/tasks/access-application-cluster/list-all-running-container-images/

Ref: https://kubernetes.io/docs/tasks/access-application-cluster/list-all-running-container-images/#list-containers-filtering-by-pod-label