@Sriram, Varun , Welcome to Microsoft Q&A! Thanks for posting the question.
Apologies for the delay! When Easy auth and CORS features are turned on a middleware docker container is created and all requests are routed through them. You could handle the CORS within the application code in order to avoid the limit. Turn off these features and implement custom authorization and CORS application code within the app service.
Kindly see the document for current .NET core middleware limitation.
Also, checkout these best practices for running Node.js WebApps: