401 Unauthorized when sending a GET request to my Github Codespaces private port from my local Postman

[yamcodes]

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Bug

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Description of the Bug

Sending a Postman or CURL request to my Codespace (-3000.github.dev) with a X-Github-Token: ghu_%rest_of_token% results in 401 Unauthorized.

Changing the Port Visibility from private to public temporarily solves the issue and returns the expected content of the request, indicating that the URL is correct.

More details

My application is forwarded through port 3000 and available for consumption with a browser (by navigating to https://%mycontainer%-3000.app.github.dev/), after authenticating by logging with Github credentials in the interactive menu.

I'm trying to achieve the same with Postman, so I can interact with my API that is hosted in the Codespace, using Postman.
It should be noted that the port is set to private, and that I have followed "Using command-line tools and REST clients to access ports" from the Github Codespaces Docs.

Here is the request/response:

$ curl https://%my_container%-3000.app.github.dev/ -H "X-Github-Token: ghu_%rest_of_token%" -I
HTTP/2 401
date: Mon, 09 Oct 2023 14:35:39 GMT
www-authenticate: tunnel
x-content-type-options: nosniff
ratelimit-limit: HttpRequestRatePerPort:3000/m
ratelimit-remaining: HttpRequestRatePerPort:2998
ratelimit-reset: HttpRequestRatePerPort:16s
vssaas-request-id: f4cec0ad-5e80-4341-ba5b-3f3805c4c5c8
strict-transport-security: max-age=31536000; includeSubDomains
x-served-by: tunnels-prod-rel-euw-v3-cluster

It should also be noted that ghu_%rest_of_token% is granted by:

echo $GITHUB_TOKEN

Inside of the codespace.

Temporary Workaround

As mentioned above:

Changing the Port Visibility from private to public temporarily solves the issue and returns the expected content of the request, indicating that the URL is correct.