Create an Azure Disk Snapshot — Portal

We regularly take new snapshots of a VMs vhds before testing major development changes, adding Windows updates, testing new application settings etc., to allow us to easily revert to the previous state of the VM if desired. In Azure, snapshots are taken of the virtual disks (vhd), not the VM instance itself. Snapshots are full, read-only copies of the vhds.

https://arlanblogs.medium.com/create-an-azure-disk-snapshot-portal-67c8417a09a9