Having installed 4.3rc2 I found after a updating and reboot that the qubes-manager (selecting VMs to start) which is an additional desktop-shortcut and the top-left-button-menue does not work anymore.
I think about a new install. Maybe someone else has the same problem too.
Maybe this helps?
I found the reason for the “screwed-up” qubes:
As I also have kali and windows on the laptop, I use multibooting with uefi and with grub. Kali is so nice that update-grub also finds qubes and the boot-menue of kali offers to boot qubes. If I choose qubes-from the kali boot menue the screwed-up behavior can be reproduced.
So I am sure that the boot parameters in grub.cfg are not in order. It seems to boot qubes-linux without XEN.
Having reinstalled Qubes, just to be sure, I can report that this build works ok as far as I have seen until now:
https://qubes.notset.fr/iso/Qubes-4.3.202510142200-x86_64.iso
The Templates need updates and also does DOM 0. There is only whonix 17 not 18.
For Whonix 18 templates, you need the rc3. The nightly rc3 build could be find here:
https://openqa.qubes-os.org/tests/157510/asset/iso/Qubes-R4.3.0-rc3pre2-x86_64.iso
Or just installing the rc2 ISO, then updating it, finally downloading the Whonix 18 templates via template manager.