As you know, Azure Services came first under what is now called ‘Classic’ resource model and has evolved to the ARM (Azure Resource Manager) model.
For quite some time, both Classic and ARM have been coexisting, allowing customers to provision Azure resource with either of the model.
Now, it is time for the Classic IaaS services to be retired. If you are still using virtual machine deployed with the Classic model, you need to start migrating them to the ARM model.
Starting now, new virtual machine deployment can only be done by using ARM deployment model while you have up to March 1st, 2023 to migrate your existing Classic VM to the ARM model.
If at this date you still have virtual machine under the Classic model you will not be able to start them – if they were running, they will be stopped.
This retirement does not impact Cloud Service, Storage Account or Virtual Network deployed using the Classic model if they are not used by a Classic virtual machine.
You can have guidance on how to migrate from Classic to ARM using this documentation https://docs.microsoft.com/en-gb/azure/virtual-machines/windows/migration-classic-resource-manager-overview