Operator doesn't apply the provided service account to the backup containers

MongoDB Percona Operator for MongoDB
2

For the benefit of someone stumbling upon this thread, my current workaround is via a ClusterPolicy using kyverno. The helm hook is to ensure it installs before anything else, so when the operator spawns a statefulset kyverno is ready.

---
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: s3-access-service-account-stateful-set
  annotations:
    policies.kyverno.io/title: Add s3-access service account to operator StatefulSet
    policies.kyverno.io/subject: StatefulSet
    policies.kyverno.io/minversion: 1.6.0
    policies.kyverno.io/description: >-
      Due to an issue with the percona operator, we can't set the correct service account to the
      pods of the stateful set that make the replica set in order to get s3 access.
      This automation will mutate operator stateful sets.
    "helm.sh/hook": pre-install,pre-upgrade
spec:
  rules:
    - name: percona-operator-stateful-sets
      match:
        any:
          - resources:
              kinds:
                - StatefulSet
              labels:
                app.kubernetes.io/managed-by: percona-server-mongodb-operator
      mutate:
        patchStrategicMerge:
          spec:
            template:
              spec:
                serviceAccount: my-service-account
                serviceAccountName: my-service-account