What could be the problem when running flask app?

Question

Flask

We have a standard structure:

app/
__init__.py
routes.py
site.py

contents of
init.py files:

application = Flask(__name__)

from app import routes
if __name__ == '__main__':
    application.run(debug=True)

routes.py

from app import application
@application.route('/')
@application.route('/index.html')
def index():
    return render_template("index.html")

site.py

from app import application
application.run(debug=True, port=5000)

on startup it says:
* Serving Flask app "app" (lazy loading)
* Environment: production
WARNING: This is a development server. Do not use it in a production deployment.
Use a production WSGI server instead.
* Debug mode: on and not

a line about what port the server is running on (((

what could be the problem? the service is available on the port, however, when starting, the flask persistently does not want to give a reference to the port