The get and getlist here a specific thing for Flask in python. To obtain values of request variables using Python you simple use the request.form.get
payload = request.form.get("payload")To retrieve and make sure what you actually retrieve if it’s a value or array.
payload = request.form.getList("payload")Flask request documentation: https://flask.palletsprojects.com/en/2.2.x/api/#flask.Request