Installer stuck on macOS trying to install a non-existant update

I have a macOS installation with 6.4.3 and 6.5.0-beta3 (both iOS and macOS) installed and wanted to add a missing Qt module:

Clicking "Add or remove components" just tells me "There is an important update available. Please select Update Components first" and doesn't let me continue.

But "Update components" shows a list of stuff that's all greyed out, I can't select anything and can't click on "Next", as that is disabled as well.

So I'm stuck ... the only option I see is to uninstall everything and start from scratch.

For the record: InstallationLog.txt doesn't have anything out of the ordinary.

Built with Qt Installer Framework 4.5.2

Based on Qt 5.15.11

Built on Feb 22 2023

From revision 11b047c49f383bdaad9495d95548919631825452