Steps to reproduce:

oc new-project foo

cat << EOF| oc create -f -
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: allow-from-openshift-ingress
spec:
  ingress:
  - from:
    - namespaceSelector:
        matchLabels:
          policy-group.network.openshift.io/ingress: ""
  podSelector: {}
  policyTypes:
  - Ingress
EOF

cat << EOF| oc create -f -
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: allow-from-openshift-monitoring
spec:
  ingress:
  - from:
    - namespaceSelector:
        matchLabels:
          network.openshift.io/policy-group: monitoring
  podSelector: {}
  policyTypes:
  - Ingress
EOF

cat << EOF| oc create -f -
kind: NetworkPolicy
apiVersion: networking.k8s.io/v1
metadata:
  name: allow-same-namespace
spec:
  podSelector:
  ingress:
  - from:
    - podSelector: {}
EOF

cat << EOF| oc create -f -
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: allow-from-kube-apiserver-operator
spec:
  ingress:
  - from:
    - namespaceSelector:
        matchLabels:
          kubernetes.io/metadata.name: openshift-kube-apiserver-operator
      podSelector:
        matchLabels:
          app: kube-apiserver-operator
  policyTypes:
  - Ingress
EOF

oc create deployment foo --image=quay.io/fedora/fedora – python3 -m http.server
oc create service clusterip foo --tcp=8000
oc patch svc foo --type merge --patch '{"spec":{"type":"LoadBalancer"}}'
oc new-project bar
oc debug – curl -sLo /dev/null -w '%{http_code}\n' <EXTERNAL-IP>:8000

Actual results: The ExternalIP is accessible on OpenShiftSDN and not accessible on OVN-K.