Exam AWS DevOps Engineer Professional topic 1 question 55 discussion

A DevOps engineer sets up two Amazon S3 event notifications for an S3 bucket from the S3 console. Both event notifications will be invoked when an object PUT action occurs. One event notification will invoke an AWS Lambda function if the file suffix is .csv. Another event notification will invoke an Amazon Simple
Notification Service (Amazon SNS) topic if the file suffix is .xlsx
The DevOps engineer notices that files with the .csv suffix can invoke the Lambda function successfully. However, files with the .xlsx suffix cannot invoke the SNS topic.
Which reason explains why the SNS topic is not invoked when .xlsx files are added to the S3 bucket?