VMs in all clouds are always tied to specific machines. If that machine fails unexpectedly then those VMs will restart. If it is a controlled reboot (e.g. host update) then they may not restart...
On Google's cloud, at least, VMs don't get killed for planned hypervisor downtime, which is a potential differentiator for them. Of course, this should matter a lot less for workloads that have been explicitly designed run on Kubernetes...
Well, at least in Google Cloud for planned updates you can get your VM host migrated and not lose a Node due to a planned maintenance. I am not aware if Azure supports this, but my guess is they do not.