Currently delving into the realm of Vue JS, I have grasped the concept of Vue JS <-> AWS Cognito authentication process and the integration of Vue JS <-> Flask. I am now curious to explore how to authenticate a user using AWS Cognito with Vue JS as the frontend. Moreover, once authenticated, I want to understand how to securely access Flask Backend APIs. How exactly does Flask validate authentication data (such as the JWT Token passed from AWS Cognito to Vue) provided by Vue JS in order to respond to API requests?