AWS Backup - copyjob rds snapshot - destination backup kms issue bug

Followed this tutorial : https://aws.amazon.com/blogs/storage/protecting-amazon-rds-db-instances-encrypted-using-kms-aws-managed-key-with-cross-account-and-cross-region-backups/

Here is the issue -

When the backup rds was performed in the Region A's vault - it has its kms customer-key. But when it was copied over using the aws backup copyjob operation into region B's vault, the backup in destionation region B has the region B's aws managed keys rds when it was supposed to have the customer key kms of region A's replica (in region B).

Note: the customer key in region A is multi-region and has a replica of it in region B