I switched from 4.0.4 to 4.1.0-beta1, with the new-install-and-backup/restore process. I chose Debian as main template and dvm-based sys-{net,firewall}.
After some settings, now all works except minor cases. Thanks for all the work done by the Qubes-OS team! 
The minor cases:
- fedora-34 template update: salt error when updating from the tray-bar update (and so also from qubectl/salt cli), but works from Qubes Manager / update. The salt update works for debian and whonix. I’ll explore this in the next days, and create an issue if it’s a real problem.
- Debian Disposable VM doesn’t work. The debian-10-dvm works for my sys-* but not for disp-{1234}. Maybe a mistake in my restore process, I’ll fix this in the next days.
- my old webcam no more detected