I have a 3rd party Helm chart with deploys the application via our Flux HelmRelease definition. Now we have the requirement that we need to inject a container into a StatefulSet rendered by the Helm chart. So my approach is to use Helm's postRederer hook to patch the generated yaml and inject the container.

However I'm having troubes enhancing an existing HelmRelease definition with a postRenderers configuration using kustomize's patchesStrategicMerge patch strategy. Based on the example here I'm trying to add the following yaml snippet to the code:

  postRenderers:
    - kustomize:
        patchesStrategicMerge:
          - kind: StatefulSet
            apiVersion: apps/v1
            metadata:
              name: dx-blue-core
            spec:
              template:
                spec:
                  containers:
                    - args:
                        - infinity
                      command:
                        - sleep
                      env:
                        - name: ENVIRONMENT
                          value: dev-2
                        - name: TESTER
                          value: hhue-2
                      image: 'nginx:latest'
                      imagePullPolicy: IfNotPresent
                      name: filebeat

However no matter if I do a oc edit helmrelease dxb or do it via ArgoCD's edit function the the code is reverted back to:

  postRenderers:
    - kustomize: {}

and I can't find any hint on what's wrong.

Running 2.3.0 on OpenShift using the Flux operator provided by the Flux project.

What am I doing wrong? Is it because of the deprecation of the strategic merge?