Use Docker-Secrets for Postgres-Credentials in Spring (bis)

I have the same problem than here and here, but not the same cause, I have no extra character in my password file.

I am working with odoo, Postgres and docker-compose. I want to use secrets for the database user and password but it does not work:

version: '2'
services:
  db:
    container_name: odoo_db
    image: postgres:14
    user: root
    environment:
      - POSTGRES_DB=postgres
      - POSTGRES_USER=odoo
      - POSTGRES_PASSWORD_FILE=/run/secrets/postgresql_password
    volumes:
        - ./postgresql:/var/lib/postgresql/data
    secrets:
      - postgresql_password
    ports:
      - 5432:5432
    restart: always             # run as a service

  odoo15:
    container_name: odoo_web
    image: odoo:15
    depends_on:
      - db
    user: root
    volumes:
      - ./addons:/mnt/extra-addons
      - ./etc:/etc/odoo
    ports:
      - "10013:8069"
    tty: true
    command: --
    environment:
      - HOST=db
      - USER=odoo
      - PASSWORD_FILE=/run/secrets/postgresql_password
    secrets:
      - postgresql_password
    restart: always             # run as a service

secrets:
  postgresql_password:
    file: odoo_pg_pass

My password file odoo_pg_pass contains only: 123 with no space and no CR or LF.

Here is the error message:

odoo_db   | 2022-09-13 06:43:00.880 UTC [1058] FATAL:  password authentication failed for user "odoo"
odoo_db   | 2022-09-13 06:43:00.880 UTC [1058] DETAIL:  Connection matched pg_hba.conf line 100: "host all all all scram-sha-256"

EDIT: if I suppress the secret file and use environment variable POSTGRES_PASSWORD without _FILE, it works with a password like odoo, but not with 123. I need more testing.

EDIT: more testing results: with odoo as a pasword, the secret mechanism with use of the environment variable POSTGRES_PASSWORD_FILE works, but not with another password. It is like if the password was hardcoded somewhere. But I have checked with a recursive grep and found nothing suspect in the whole tree.

EDIT: if I change the POSTGRES_USER in db and USER in odoo15 to something different than odoo, I have the same problem.