Django (App Platform) Migrate Command raises ERROR: "could not translate host name '[...]' to address: Temporary failure in name resolution'

I re-deployed my Django App on DO’s app platform but I am facing a new issue that I did not encounter before. Once successfully deployed, when I try to go into the console and run Django’s Migrate Command (python manage.py migrate) the following error is raised:

django.db.utils.OperationalError: could not translate host name “app-[…].db.ondigitalocean.com” to address: Temporary failure in name resolution

1. The host name should be correct and in my App I use the following Environment Variables:

POSTGRES_DB: ${db.DATABASE}
POSTGRES_HOST: ${db.HOSTNAME}
POSTGRES_USER: ${db.USERNAME}
POSTGRES_PASSWORD: ${db.PASSWORD}
POSTGRES_PORT: ${db.PORT}
DATABASE_URL: ${db.DATABASE_URL}

2. My Database configuration in settings.py:

DATABASES = {
    "default": {
        "ENGINE": "django.db.backends.postgresql_psycopg2",
        "HOST": os.getenv("POSTGRES_HOST"),
        "NAME": os.getenv("POSTGRES_DB"),
        "PASSWORD": os.getenv("POSTGRES_PASSWORD"),
        "USER": os.getenv("POSTGRES_USER"),
        "PORT": os.getenv("POSTGRES_PORT", 0),
    }
}

3. The Database is called db (default).

4. I can connect to the database with the given connection details with my local PostgreSQL client.

I don’t know what else to try. Thanks in advance!