Q. What happens if a Hyper-V VM has a newer set of integration services than that of the Hyper-V host?

A. A recent change for Hyper-V related to the integration services (the services which enable communication between the guest OS and the hypervisor to bring an enhanced virtualization experience such as backup, heartbeat etc) is that the integration services are updated through Windows Update instead of an integration services disk which was updated when the host was updated.

This change was made as VMs became more mobile between hypervisor instances (and even between versions for example between 2012 R2 and 2016) which meant tying the integration service version to that of the host was no longer logical. It was more beneficial to have VMs running the latest version and enable integration services to detect the hypervisor version and adjust the functionality which enables a integration services that are newer than the hypervisor to carry on running.

This means there is no problem if the VM has newer integration services than that of the hypervisor be it version of the OS or patch levels (as often guest VMs are on a different patch schedule than that of the hosts).