A bridge is created automatically during join and KVM virtualisierungsserver is preselected during installation. This was not expected.
The bridge is created when ‘univention-virtual-machine-manager-node-kvm’ is installed. Then the bridge is created from the postinst script, if the ucr variable uvmm/kvm/bridge/autostart is not set to no/manually.
In this special szenario a policy or a PXE Installation value set this variable to yes.