I/O request charges are still coming after converting Aurora I/O Optimized from Aurora Standard

Just to make sure what you're currently being charged for, perhaps you could quickly check the following:

• Open the Billing and Cost Management console
• Open Cost Explorer

On the right side of the screen

• For "Date range", select June 1st as the start date and August 7th as the end date (data for the past 2 days is incomplete)
• Set "Granularity" to "Daily"
• Set "Dimension" to "Usage type"

In the "Filters" section below

• Set "Service" to "Include" "Relational Database Service (RDS)"
• Set "Charge type" to "Exclude" the type "Tax"

This will give you a daily breakdown of your RDS costs. The graph shows the biggest cost items, and the table below shows all the usage types and daily charges for each one.

Can you find the unwanted charges in the table view below? If so, are the unwanted costs stable until August 7th, or have they changed or ceased after the day you made your capacity changes?

The I/O request charge is normal and specifically charged for the Standard cluster type, not for the I/O-Optimized type: https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/Aurora.Overview.StorageReliability.html#aurora-storage-type and https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/User_DBInstanceBilling.html