CORS issues behind nginx ingress after updating to JupyterHub 2.1.1

I am using AWS’s Classic Load Balancer

Documentation states the following:

Application Load Balancers and Classic Load Balancers automatically add X-Forwarded-For , X-Forwarded-Proto , and X-Forwarded-Port headers to the request.

So, I am not sure where the issue lies: in load balancer, nginx ingress or JupyterHub?