How to block a traffic from a pod x in namespace x to all pods in namespace y ? . . .

Balaji K:
How to block a traffic from a pod x in namespace x to all pods in namespace y ? I tried matchExpressions with NotIn didn’t work. Any betterway to do…
Here is what I did

apiVersion: <http://networking.k8s.io/v1|networking.k8s.io/v1>
kind: NetworkPolicy
metadata:
name: netpoletcdchf
namespace: y
spec:
podSelector: {}
policyTypes:
- Ingress
ingress:
- from:
- podSelector:
matchExpressions:
- {key: app, operator: NotIn, values: [x]}

unnivkn:
Hi… please read the last item in the attached screenshot.