Cannot filter out json key from json formatted log using loki with Grafana Agent

Grafana Configuration
1

Here’s the related configuration of my Grafana Agent:

scrape_configs:
    - job_name: integrations/messages
      static_configs:
      - targets:
        - localhost
        labels:
          instance: server1.company
          unit: api-messages
          __path__: /var/log/company/company-api.log
          job: integrations/node_exporter
      pipeline_stages:
        - replace:
            expression: "(.*org.zalando.logbook.Logbook[ ]*:[ ]*)"
            replace: ""
        - template:
            source: message
            template: '{{ omit (mustFromJson .) "body" | mustToJson }}'
        - json:
            expressions:
              origin: origin
              type: type
              correlation: correlation
              duration: duration
              protocol: protocol
              status: status
              headers: headers
              remote: remote
              method: method
              uri: uri
              host: host
              path: path
              scheme: scheme
              port: port
        - labels:
            origin:
            type:
            correlation:
            duration:
            protocol:
            status:
            headers:
            remote:
            method:
            uri:
            host:
            path:
            scheme:
            port:

Basically I have a log line which starts with a prefix (and removed in replace stage). The rest is a nested json, where I want to remove body from being transferred to Grafana Cloud:

{"origin":"local","type":"response","correlation":"94268499157e62c9","duration":8,"protocol":"HTTP/1.0","status":200,"headers":{"Cache-Control":["no-cache, no-store, max-age=0, must-revalidate"],"Connection":["close"],"Content-Type":["application/json"],"Date":["Sun, 01 Jun 2025 19:24:33 GMT"],"Expires":["0"],"Pragma":["no-cache"],"X-Content-Type-Options":["nosniff"],"X-Frame-Options":["SAMEORIGIN"],"X-XSS-Protection":["1; mode=block"]},"body":"SOME_ACTUAL_NESTED_JSON_REQUEST_BODY HERE"}

The body is not parsed, and no label named body is created, but it is visible in Log Context, (i.e. raw log line is being transferred to Grafana Cloud, after the replace. Replaced part is not visible.)

What am I doing wrong, how do I skip body (or replace it with XXX) before the Log context is even created? The body might be nested JSON.