How to authenticate a user when reporting a custom_event using python in appinsight

I am trying to trigger a custom event in a python application to record a system action linked to a specific user.

Our front end application provides a user_Id and user_AuthenticatedId to app insight and I want to populate the later at least in the backend side somewhere (I don't have access to the operations etc, only the UserId)

The only code I got functioning do trigger the custom event

from azure.monitor.opentelemetry import configure_azure_monitor
from azure.monitor.events.extension import track_event

configure_azure_monitor(
    disable_offline_storage=True,
    logger_name="telemetry"
)

def my_actual_function():
  ...
  track_event(
    "test-custom-event",
    {
      "user_AuthenticatedId": "toto",
      "user_Id": "1111000003333",
      "data": json.dumps({"test": 'OK'}),
    }
  )
  ...

but there is no linked user in app insight, in the first line corresponding to my "test-custom-event" the user columns are empty