RDS snapshots are not deleted and continue to be billed

Hello.

I gave the same answer in the question below, but what you're seeing is a public snapshot, so it's a snapshot that won't be billed to your AWS account.
Therefore, you need to check whether there are any snapshots left in another region.
https://repost.aws/ja/questions/QUu4kbrfWnSoe422ueeKMnAA/the-reason-for-the-amount-being-charged-is-unknown

1. Identify the Snapshots:

Go to the Amazon RDS console.

Navigate to Snapshots in the left-hand menu.

Identify the snapshots that are incurring charges.

2. Determine the Owner of the Snapshots:

If the snapshots are part of your account, you should be able to see their details and ownership information.

Snapshots may be shared with your account, but only the owner can delete them. If they were created by another AWS account, you'll see an indication that they are shared.

3. Delete the Snapshots:

If the snapshots belong to your account, you can select them and click Delete.

If the snapshots are shared and you can't delete them:

You can stop the sharing by contacting the owner or using the Modify Snapshot Permissions option if available.

If the snapshots are part of an automated backup or linked to an active RDS instance, you may need to delete the associated RDS instance first.

4. Contact AWS Support:

If you're unable to delete the snapshots or determine their ownership, you should contact AWS Support for assistance.

Open a support case explaining the situation. AWS Support can help you understand why these snapshots are there and assist in deleting them if they are orphaned or mistakenly billed to your account.

5. Review and Monitor Billing:

Go to the Billing Dashboard and review the charges related to RDS snapshots.

Set up billing alerts or a cost budget to avoid unexpected charges in the future.

You can also enable AWS Free Tier Usage Alerts to monitor any charges if you are under the free tier.

6. Account Closure (Optional): If you no longer need the AWS account and want to avoid any future charges, you can proceed with closing the account. But make sure to delete all resources, including RDS snapshots, to prevent any further charges.

https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_DeleteSnapshot.html#:~:text=If%20you%20have%20automated%20DB%20snapshots%20that%20you,want%20to%20wait%20until%20the%20next%20maintenance%20period.