I found this url for best practices for Azure resource naming conventions. It has list of prefixes based on resource type. I don't find prefix for Azure SQL Server in it. It has prefix for Azure SQL Database but not Server. Is there a 'standard' naming convention for Azure SQL Server?
I think even though naming convention for Azure SQL Server is not explicitly specified in the url, by extrapolating naming conventions for the mentioned resources we can say that prefix for Azure SQL Server resource should be sqls-. And accordingly the format for the resource should be sqls-<App Name>-<Environment>.