Why is the task-definition created as a stack in cloudformation when creating aws ecs fargate?

The aws ecs fargate is being deployed through the aws cli using the console for only the task definition and the rest of the cluster, service container, and deployment.

One day, I saw that the task definitions were created as stacks in cloudformation. (Failure records were also included.)

Searching or looking at the official documentation says that the stack is not created in cloudformation. What is the cause? And how to prevent it from spawning?

I created it by referring to the following document. https://docs.aws.amazon.com/AmazonECS/latest/developerguide/create-blue-green.html