Private endpoint in Azure

From that error message:PrivateEndpointCannotBeCreatedInSubnetThatHasNetworkPoliciesEnabled,

You could disable network policies for private endpoints in that subnet virtualNetworks/plink-vnet-2/subnets/plsubnet with Azure PowerShell or Azure CLI or template.

For example, using Azure CLI,

az network vnet subnet update \ 
  --name default \ 
  --resource-group myResourceGroup \ 
  --vnet-name myVirtualNetwork \ 
  --disable-private-endpoint-network-policies true

In the portal, I'm assuming you are doing this from the sql database create. You should be able to create a sql database without a private endpoint and then use the individual private endpoint create as it will properly handle disabling the network policies in the subnet for the private endpoint. You can find the individual private endpoint create as the first start button in the overview of the Private Link Center.