$AZURE_CONTAINERAPPS_ENV_DEFAULT_DOMAIN can not be applied

[vienleidl]

After run the az containercompose create command with the following docker-compose file, the value of SERVER_HOST environment var hasn't been applied correctly. The result is SERVER_HOST => nginx. in Container App's environment variables.

version: '3.4'
services:
  app:
    image: 'ACR_NAME.azurecr.io/Repo_Name/Image_Name:Tag_Name'
    environment:
      - HOST=0.0.0.0
      - PORT=8080
      - SERVER_PROTOCOL=HTTP
      - SERVER_HOST=nginx.$AZURE_CONTAINERAPPS_ENV_DEFAULT_DOMAIN
      - SERVER_PORT=80
      - SERVER_PATH=/app

If it's updated as nginx.$$AZURE_CONTAINERAPPS_ENV_DEFAULT_DOMAIN => the result will be SERVER_HOST => nginx.$