SfsClient do not handle Kerberos Authentication for proxy

Relevant area(s)

WinGet CLI

Relevant command(s)

winget download

Brief description of your issue

winget download --id 9NBLGGH4QGHW --Source MSStore --accept-package-agreements --accept-source-agreements
results in:
"Fehler beim Abrufen von Microsoft Store Paketdownloadinformationen"

Steps to reproduce

run cmd or powershell
run:
winget.exe download --id 9NBLGGH4QGHW --Source MSStore --accept-package-agreements --accept-source-agreements --proxy="http://proxyxxxxx:" --verbose-logs

winget is asking for the entra id.
answer the question with "No, only this app"
-> error

Expected behavior

downloading the package with dependencies

Actual behavior

download try results in error message:
"Fehler beim Abrufen von Microsoft Store Paketdownloadinformationen"

WinGet-2025-08-25-14-03-54.298.log

Environment

Windows-Paket-Manager v1.11.430
Windows: Windows.Desktop v10.0.22631.5771
Systemarchitektur: X64
Paket: Microsoft.DesktopAppInstaller v1.26.430.0

Start with the winget.exe download command and the SfsClient proxy path, using the attached verbose log to trace the failed Microsoft Store request. Reproduce through a Kerberos-authenticated proxy and confirm that package downloads with dependencies complete successfully without the reported error.