The problem is that you have provided a wrong subnet ID, the correct format is that
/subscriptions/<subscriptionID>/resourceGroups/<rgName>/providers/Microsoft.Network/virtualNetworks/<vnetName>/subnets/<subnetName>
You can get the subnet ID via
az network vnet subnet show -g <rgName> -n <subnetName> --vnet-name <vnetName> --query id -o tsv
You lack the resource group name in your providing subnet ID.
subscriptions/xxxx/resourceGroups/providers/Micosoft.Network/virtualNetworks/rg-sql-cpe-poc-eastus-001/vnet-primary-poc-eastus-001/subnets/snet-mgmt-poc-eastus-002
Result
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…