Filebeat JSON string

[NFhbar]

I have a filebeat configuration as follows:

filebeat.yml: |-
    filebeat.autodiscover:
      providers:
        - type: kubernetes
          hints.enabled: true
          templates:
            - condition:
                equals:
                  kubernetes.namespace: default
              config:
                - type: docker
                  containers.ids:
                    - "${data.kubernetes.container.id}"
                  processors:
                    decode_json_fields:
                      fields: ["message"]
                      target: ""
                      process_array: false
                      max_depth: 10
                      overwrite_keys: false
                    add_kubernetes_metadata:
                      in_cluster: true

    output.logstash:
      enabled: true
      ssl.enabled: true
      hosts: ["logstash.chargepayments.io:8751"]
      ssl.certificate_authorities: ["${path.config}/keys/ca.crt"]
      ssl.certificate: "${path.config}/keys/client.crt"
      ssl.key: "${path.config}/keys/client.key"

Which then sends my logs to logstash. I can see this logs in Kibana but the message is a JSON string (line 46):

How can I have this field be a JSON object?