Don't require namespace for ignoreDifferences

argocd/app-of-apps/templates/applications.yaml

@@ -18,7 +18,9 @@ spec:
       group: {{ .group }}
       {{- end }}
       name: {{ .name }}
+      {{- if .namespace }}
       namespace: {{ .namespace }}
+      {{- end }}
       jsonPointers:
         {{- toYaml .jsonPointers | nindent 10 }}
     {{- end }}

argocd/app-of-apps/test/values.yaml

@@ -57,10 +57,9 @@ applications:
     serverSideApply: true
     syncWave: 2
     ignoreDifferences:
-      - group: ""
+      - group: "*"
         kind: PersistentVolume
         name: prometheus-prometheus-pv-0
-        namespace: observability
         jsonPointers:
           - /spec/claimRef/resourceVersion
           - /spec/claimRef/uid