Unable to get .coverage file in local system when using docker compose up

I am unable to get .coverage file in local system when using docker compose up. But .coverage file is getting emitted in case of docker compose run command but not in up

I am mounting my current working directory in docker container, and also changing the current working directory in container to the current dir in local.

the below is my docker-compose file:

services:
  flask-app:
    image: flask-app:1.0
    container_name: flask-app
    build:
      context: .
    ports:
      - "6000:6000"
    volumes:
      - ${PWD}:${PWD}
    working_dir: ${PWD}

https://github.com/AkashKumar7902/flask-app
the above is a minimalist reproducible app.

First run docker compose up and stop the app, you won't find any .coverage file.
After that, run docker compose run flask-app, the difference can be seen.

Reproduce the behavior with the linked minimalist flask-app and the provided compose file, comparing docker compose up with docker compose run flask-app. Then trace how coverage data is written during container startup and shutdown. Done means the behavior is explained and a verified change or documented limitation addresses the missing .coverage file.