As advertised in qubes-users mailing list, the templates of whonix version 14 is now available and flawlessly installed on my Qubes 4.0, without much effort.
I had no issues, so after deleting all existing whonix templates and AppVM‘s, the steps to follow were:
sudo dnf remove qubes-template-whonix-ws
sudo dnf remove qubes-template-whonix-gw
sudo qubesctl state.sls qvm.anon-whonix
sudo qubesctl state.sls qvm.whonix-ws-dvm
And then use Chris Laprise’s script to update them:
./qubes4-multi-update whonix-gw-14 whonix-ws-14
I rarely use whonix, but nonetheless, I encourage anyone using it for good, to donate, supporting the project.