I managed to use system vm-image instead of system vm and I have to say it fares better
I can fiddle with qemu switches and I managed to allow my virtual machine to reach out on the network, The machine is faster and less awkard, the terminal background is dark instead of sun bright So this bug is not urgent But I still think this is a bug. system vm is a Guix feature and the machine it provides should be able to get on the network, I think