IAM role ARN value is invalid or does not include the required permissions for: S3_SNAPSHOT_INGESTION

If you need an IAM role to import your database from Amazon S3, create a role to delegate permissions from Amazon RDS to your Amazon S3 bucket.

check this

https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/MySQL.Procedural.Importing.html#MySQL.Procedural.Importing.Enabling.IAM

https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/MySQL.Procedural.Importing.html#MySQL.Procedural.Importing.PerformingImport

The error message you're encountering suggests that the IAM role associated with your RDS instance does not have the necessary permissions to access the S3 bucket containing the database snapshot. To resolve this issue, you need to update the IAM role's policy to include the required permissions for S3 snapshot ingestion.