Docker loki logs processing not forwarding container labels to writer

Grafana Grafana Agent
1

I have configured an agent in flow mode to get logs from docker containers. (see config below)
All the default labels from discover.docker / loki.docker seems not being forwarded to loki.
Documentation is not really clear on how to set this up.
I know how to extract details from the log itself, but my question is more about the default labels from the docker container. How do I add these as labels?

discovery.docker "linux" {
  host = "unix:///var/run/docker.sock"
}

loki.source.docker "default" {
  host       = "unix:///var/run/docker.sock"
  targets    = discovery.docker.linux.targets
  forward_to = [loki.process.logs.receiver]
}
loki.process "logs" {
  forward_to = [loki.write.local.receiver]
  stage.docker {}
  stage.static_labels {
    values = {
      env = "TEST",
    }
  }
}
loki.write "local" {
  endpoint {
    url = "http://host:3100/loki/api/v1/push"
  }
}