Azure Function Proxy Cookie in Original Request Is Truncated When Routed to BackendUri

Question

We are using proxies.json to set up proxies for some of our API requests (where the endpoints are Azure functions). However, when the request is routed to the backend uri, and the Azure function at the endpoint is executed, we see that the cookie has been truncated.

The cookie is a fairly long token (about 2K). It is stored in the original request header in the format:

Identity=[2K cookie]

But again, when we pull it from the HTTP Request while executing the Azure function (endpoint), we find that it has been truncated to a shorter length (approx 1600 bytes). Is there some reason why this might happen?