AWS SageMaker Notebook instances do not have data encryption enabled which may cause exposure of sensitive data.
In AWS Console -
In Terraform -
References:
https://docs.aws.amazon.com/sagemaker/latest/dg/encryption-at-rest.html
https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/sagemaker_notebook_instance#kms_key_id