Changing Subscription won't affect the downtime, it will just you change the billing. You would need to redeploy the VM. After you redeploy a VM, the temporary disk is lost, and dynamic IP addresses associated with virtual network interface are updated.
From Overview there is no option to move the VM to another hardware to skip the maintenance.
Ideally you need an Availability Set and defining the Update Domains.
Reference:
https://docs.microsoft.com/en-us/azure/virtual-machines/windows/redeploy-to-new-node