The logic of the password configuration for the appliance configuration differs from the VM password when using keyvault authentication. This results in the appliance password being saved in the statefile as plain-text. Please add the same logic here as used for the vm password: var.az_keyvault_authentication ? data.azurerm_key_vault_secret.bigip_admin_password[0].value : random_string.password.result
Slight nuance, since the implementation of the kv auth is done in the .tmpl file this is not as much of an issue as it is not used on the actual appliance.
https://github.com/F5Networks/terraform-azure-bigip-module/blob/75d82de293ec555dae4b51f22931af9ca6464a1d/main.tf#L463
The logic of the password configuration for the appliance configuration differs from the VM password when using keyvault authentication. This results in the appliance password being saved in the statefile as plain-text. Please add the same logic here as used for the vm password:
var.az_keyvault_authentication ? data.azurerm_key_vault_secret.bigip_admin_password[0].value : random_string.password.result