AWS Backups Versus Amazon Fsx for Windows File Server Backups

Hello.

FSx backups with AWS Backup are incremental backups, so I think the cost is probably the same as standard FSx backups.
Therefore, if you have requirements such as a retention period of 90 days or more or sharing backups cross-region or cross-account, I think it would be a good idea to use AWS Backup.
https://docs.aws.amazon.com/aws-backup/latest/devguide/whatisbackup.html
https://aws.amazon.com/fsx/windows/pricing/?nc1=h_ls

I also recommend that you open a case with AWS Support under "Account and billing" for detailed cost questions.
Inquiries under "Account and billing" can be made using the free support plan.
https://docs.aws.amazon.com/awssupport/latest/user/case-management.html