500 error only in privacy mode (chrome)

We have a NSS 5.2.3 (Docker Container) running in our kubernetes behind traefik with a certificate by lets encrypt.

We are testing the chess app (https://pheyvaer.github.io/solid-chess/) and it's working for a normal chrome session.

But in privacy mode or in Chromium, we will got the following error for the GET request https://localhost/inbox/ with status 500:
request to https://localhost/.well-known/openid-configuration failed, reason: unable to verify the first certificate

We tested also against inrupt.net and there is no problem.

We compared the requests and found out, that the cookie nssidp.sid is missing.

We tried some startup parameters, but with no effect.

We think that is not a specific NSS issue more like general purpose for proxying or security measures.

Inizia riproducendo la richiesta GET a https://localhost/inbox/ nella modalità privacy di Chrome o in Chromium e confrontala con una sessione normale. Traccia l’errore di verifica del certificato per /.well-known/openid-configuration e il cookie nssidp.sid mancante attraverso NSS, Docker, Kubernetes e Traefik; il lavoro è completato quando la richiesta ha esito positivo senza l’errore 500.