VMs created prior to v4.14 have ordinal naming scheme for their secondary pod interfaces (net1, net2..netN).

These VMs retained this naming scheme though migration, and thus through upgrade.

An upgrade path for these VMs will be introduced - without requiring a reboot.

The upgrade path will allow such VMs to perform NIC hotunplug, but the main motivation for having it is code simplification.

It is up to net QE to decide if and how to cover it.
https://github.com/kubevirt/enhancements/issues/111