Unable to run containerized app in Heroku, it gives me an error message "gunicorn: error: unrecognized arguments: wsgi:app"

I followed the instructions from the Heroku site https://devcenter.heroku.com/articles/container-registry-and-runtime and everything looks good until I tried to run the app. It's displaying the following message in logs:

2021-10-29T18:28:47.688122+00:00 app[api]: Deployed web (cf684620e1d5) by user d____@.com
2021-10-29T18:28:47.688122+00:00 app[api]: Release v7 created by user d@____.com
2021-10-29T18:28:59.442743+00:00 heroku[web.1]: Starting process with command gunicorn --config /gunicorn_config.py wsgi:app
2021-10-29T18:29:00.243531+00:00 app[web.1]: usage: gunicorn [OPTIONS] [APP_MODULE]
2021-10-29T18:29:00.243568+00:00 app[web.1]: gunicorn: error: unrecognized arguments: wsgi:app
2021-10-29T18:29:00.428555+00:00 heroku[web.1]: Process exited with status 2
2021-10-29T18:29:00.588879+00:00 heroku[web.1]: State changed from starting to crashed

But when I run the app in Docker Desktop (Windows) everything is working fine, no problem.

Anyone can help me please? Thanks in advance.