What are the implications of Flask-MQTT statement, "Flask-MQTT is currently not suitable for the use with multiple worker instances?"

Question

I am planning to implement a Python REST API using Flask. I plan to use the Waitress web server. I want the REST API to interact with a long-running app using MQTT. I was planning to use Flask-MQTT. I noticed a statement:

Flask-MQTT is currently not suitable for the use with multiple worker instances.

I have tried, without success, to gain an understanding of what this statement implies for my use.

I noticed that there is a Flask-MQTT extension, flask-multimqtt, that was developed to address the issue of not Flask-MQTT not being suitable for use with multiple worker instances.

I have searched the internet to gain an understanding of the implications of the statement, "Flask-MQTT is currently not suitable for the use with multiple worker instances." I have not found anything that sheds light on the statement.

I have a few questions:

1. Is there a configuration for Waitress that allows it to be used with Flask-MQTT?

2. Is there a reason not to use Flask-MQTT?

3. Would using Flask and MQTT from separate packages eliminate the concern of using multiple worker instances?