Why am I billed for over $50 for AWS RDS?

There are several possible reasons why you might be seeing RDS charges on your AWS bill even if you believe you didn't set up the service:

1. Resources in different regions: You might have RDS resources in AWS regions you don't typically check. It's important to verify all regions in your AWS account.

2. Hidden snapshots or backups: Even if you deleted RDS instances, automated backups or snapshots might still exist and continue to incur storage costs.

3. Backup retention: If you previously had RDS instances, automated backups might be retained for a period after deletion.

4. RDS Proxies: These can incur charges even if you don't see the underlying database instances.

5. Forgotten resources: You might have created an RDS instance during testing or exploration and forgotten about it.

To troubleshoot and resolve this issue:

1. Use AWS Cost Explorer to identify exactly what RDS features are generating charges. Filter by "Service" (select RDS) and "Usage Type" to see detailed information.

2. Check all AWS regions for any active RDS instances, snapshots, or automated backups.

3. Look for AWS Backup plans that might be associated with previous RDS resources.

4. Verify if there are any RDS-related resources like proxies that might still be active.

If you're certain you never created any RDS resources, there could be a billing error or potentially unauthorized account access. In this case, contacting AWS Billing Support would be your best option. They can provide a detailed analysis of your account and help identify the source of these charges.

Sources
I am still being charged for a AWS RDS even though i have deleted the database and any snapshots. | AWS re:Post
Relational Database Service Charges How to Stop | AWS re:Post
Why am I being charged money on my account? | AWS re:Post
Bill is too high | AWS re:Post