Ensure the entire Azure infrastructure doesn't have access to Azure SQL Server

Azure connections must be enabled to allow applications from Azure to connect to your Azure SQL server. When an application from Azure attempts to connect to your database server, the firewall verifies that Azure connections are allowed. A firewall setting with starting and ending address equal to 0.0.0.0 allows these connections. This option configures the firewall to allow all connections from Azure including connections from the subscriptions of other customers. Make to use Firewall VNet rules.