Why Aurora cluster of type Microsoft SQL Server is not visible in AWS App Sync Database selction

AWS AppSync currently does not support direct integration with Amazon Aurora SQL Server. AWS AppSync supports direct integration with several types of data sources including Amazon DynamoDB, Amazon Elasticsearch Service, AWS Lambda, Amazon RDS for Aurora MySQL and PostgreSQL, HTTP APIs, and others. However, it does not include support for Aurora clusters running Microsoft SQL Server.

https://docs.aws.amazon.com/appsync/latest/devguide/attaching-a-data-source.html

https://docs.aws.amazon.com/appsync/latest/devguide/rds-introspection.html