Comment 12 for bug 1999178

Thanks for the information.

Do you still have dpkg logs from that time to confirm if the package usbmuxd was installed along with the upgrade?

Here is the sequence of events that triggers this issue with a clean Lunar installation:

1) The upgrade will install the package usbmuxd. It will drop some udev configuration in /lib/udev/rules.d/39-usbmuxd.rules. This file refers to the used usbmux.
2) At some point installation scripts will start calling systemd daemon-reload during upgrade. When it happens you'll notice the upgrade process will get stuck.
3) When the upgrade process gets to the point where it calls usbmuxd's postinst script, the user will be created.

From this point on, daemon-reloads will not stuck anymore. At least not because of the user usbmux.

If you have udev rules referring to non-existent system users, you'll probably see the same thing happening.