The login to Intune Portal fails on KDE Plasma with a Misconfiguration(0) error and a [4kv4v] code in the Microsoft auth window - same machine, same user, same tenant works under GNOME, the only difference being XDG_SESSION_DESKTOP.
The root cause: Intune Portal needs the freedesktop Secret portal (org.freedesktop.impl.portal.Secret) to store auth tokens. gnome-keyring implements the Secret portal backend - KWallet does not. So on a pure KDE box the lookup fails before the registration prompt is even shown, which is why you can't proceed past login. That's also why gnome-desktop-minimal "fixes" it: it pulls in gnome-keyring and xdg-desktop-portal-gtk as dependencies.
Three things on top of plain KDE:
1. Install the keyring and the GTK portal backend: