Issues using proxy server with authentication

User reported following:
"
After upgrading our application from Qt5 to Qt 6.2 we have discovered that we can no longer make network get requests when macOS or Windows (but not Ubuntu Linux) is configured to use a proxy server that requires authentication. This was a bug reported to us by a customer. They noticed some network calls worked (which we determined were resulting in HTTP get calls to a url beginning with http, not https), while network calls that begin with https would get stuck.
"

Example project attached and steps to reproduce:

1.Normally if I run this program I see the following output when clicking the "Make Request" button

2. However, if I redirect macOS to use a proxy server (mitmproxy)  that has been configured to require authentication (by setting "proxyauth" to secret:password) I find Qt triggers an OS sheeet to pop up asking for permission to obtain the proxy server username and password from the keychain:

3.Despite providing this I find no signals are ever emitted and the application gets "stuck": 

4.When I monitor the mitmweb interface it does not even receive a network request. If I turn off authentication on the proxy server and in my macOS configuration (but still direct my machine to use the proxy server) the network call works just fine. Qt knows it's using a proxy server too:

On Qt Support tests on Windows 10 we had following error:

Once users code was modified to provide username and password:

Then the never ending popups asking for username and password occur.