Can access GUI admin interface without authentication, but Find New Printers requires an authenticated user.

[Dominic-Mayers]

I am using cups GUI admin interface on a fresh installation of Ubuntu 22.10. If I visit 127.0.0.1:631/admin I do not have to authenticate, but without authentication, if I click on Find New Printers, no printers are found. Yet I see a printer with avahi-browse -t _ipp._tcp and also directly in Settings->Printers. If I artificially force a login by clicking on Add Printer, but don't proceed ahead and instead go back to Administration and click on Find new Printers, then the printer is found. If I modify the configuration file cupsd.conf and replace

# Restrict access to the admin pages...
<Location /admin>
  Order allow,deny
</Location>

with

# Restrict access to the admin pages...
<Location /admin>
  AuthType Default
  Require user @SYSTEM
  Order allow,deny
</Location>

then I cannot reach the admin page without first seeing the login window that allows me to login and the problem is solved.

This is not at all a new issue. It was noticed five years ago here https://unix.stackexchange.com/questions/390934/cups-how-to-troubleshoot-no-printers-found-condition .