"Possible SECURITY ATTACK detected" when deploying Redis with Docker Compose

Question

Hello,

I want to deploy my Flask-Celery-Redis-SocketIO web application (it works well locally).
I uploaded a docker image regmtgscan.azurecr.io/server and use the following docker-compose.yml in my deployment center settings on Azure:

services:
    redis:
        image: mcr.microsoft.com/oss/bitnami/redis:6.0.8
        ports:
            '6379:6379'
        environment:
            ALLOW_EMPTY_PASSWORD: "yes"
    flask:
        build: server
        image: regmtgscan.azurecr.io/server
        ports:
            - '5000:5000'
        links:
            - redis
    celery:
        build: server
        image: regmtgscan.azurecr.io/server
        command: "celery -A app.celery worker --loglevel=info --uid=nobody"
        links:
            - redis
        environment:
            - AZURE_VISION_KEY
            - AZURE_VISION_ENDPOINT

(Note that I am not sure on the syntax : docker-compose uses hyphen (-) when Azure does not, for example. But this is not my problem).

When I start my App Service, I see that every container is launching but I get the following error from the Redis one :

Possible SECURITY ATTACK detected. It looks like somebody is sending POST or Host: commands to Redis. This is likely due to an attacker attempting to use Cross Protocol Scripting to compromise your Redis instance. Connection aborted.

This error shut down my app. I can't access my app URL at all.
I don't understand why I get this error and how to solve it.

Can somebody help me solving this?