Does this issue occur when all extensions are disabled?: Yes

• VS Code Version: Insiders (broke by 08eda83)
• OS Version: Windows 10

Steps to Reproduce:

1. Connect to a remote Linux host
2. Run az login
3. Browser should open at https://login.microsoftonline.com/organizations/oauth2/... but the hostname is replaced with localhost: from the querystring.

This broke by #203908, and a potential fix (which I cannot test, see microsoft/vscode-remote-release#9556) is pending review:

• Tunnel: Extend port mapping lookup also for querystring (take 2) #204807