EACCES: permission denied with custom user and group ID

MongoDB Percona Operator for MongoDB
1

Description:

For the following CR config, with custom runAsUser and runAsGroup:

  replsets:
  - containerSecurityContext:
      allowPrivilegeEscalation: false
      capabilities:
        drop:
        - ALL
    name: rs0
    podSecurityContext:
      fsGroup: 10001
      runAsGroup: 10001
      runAsNonRoot: true
      runAsUser: 10001

perconaservermongodbs CR status ends up in error:

status:
  conditions:
  - lastTransitionTime: "2025-05-28T11:29:21Z"
    message: 'handleReplsetInit: no mongod containers in running state'
    reason: ErrorReconcile
    status: "True"
    type: error
  message: |
    Error: handleReplsetInit: exec add admin user: command terminated with exit code 1 / Warning: Could not access file: EACCES: permission denied, mkdir '/.mongodb'
     / MongoServerError: not primary
  ready: 0
  replsets:
    rs0:
      ready: 0
      size: 0
  size: 0
  state: error

Version:

Kubernetes v1.29.9+k3s1
Operator 1.19.1
Database 8

How do you run the MongoDB operator and replica sets in Kubernetes environments that do not allow running containers as root user/group?