Azure - Terraform dynamic counts index issue when azure disk encryption is applied

I have a azure infra created using terraform using a count variable with count as 2, so it creates two VMs with disks and disk encryption also applied, but when I increase the VM count by increasing the count to 3, it works according to my script by creating a 3rd VM and its dependent resources but it also again recreates the data disk of other two VMs I. vm1 & vm2. in terraform plan it shows the encryption forces replacement.

attached below plan.

azurerm_managed_disk.externalweb[0] must be replaced

-/+ resource “azurerm_managed_disk” “externalweb” {
create_option = “Empty”
~ disk_iops_read_write = 500 -> (known after apply)
~ disk_mbps_read_write = 60 -> (known after apply)
disk_size_gb = 10
~ id = “/subscriptions/xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx” -> (known after apply)
location = “eastus”
name = “WEBVM1”
resource_group_name = “GCH_INTEGDEV_EUSrg2”

  • source_uri = (known after apply)
    storage_account_type = “Standard_LRS”
    ~ tags = {} -> (known after apply)
  • zones = -> null

  • encryption_settings {

  • enabled = true -> null # forces replacement

can anyone suggest me how can I rid the replacement/re-creation of my data disk again everytime I scale out & in the infra.