Why is there a discrepancy in the use of Read/Write IOPS between the Aurora PostgreSQL Cluster and a single instance inside it?

Hi there,

community, I need help with determining why my Aurora PostgreSQL Cluster uses much more IO than a single instance inside it. Here is some info

Here are the settings examples I'm using for these charts.

Is there anything in cluster monitoring that can help me define why the cluster is using much more IO (we need to pay for) than a single instance inside it?

My cluster settings are:

1. DB cluster role - Regional cluster
2. Engine version - 12.16
3. RDS Extended Support - Enabled
4. Cluster storage configuration - Aurora Standard
5. Network type - IPv4
6. Capacity type - Provisioned
7. DB cluster parameter group - default.aurora-postgresql12
8. Availability - Multi-AZ No
9. Database activity stream - Status Stopped

My instance settings are:

1. Engine version - 12.16
2. RDS Extended Support - Enabled
3. Option groups - default:aurora-postgresql-12
4. DB instance parameter group - default.aurora-postgresql12
5. DB cluster parameter group - default.aurora-postgresql12
6. Architecture settings - Non-multitenant architecture
7. Instance class - db.r6g.large
8. vCPU - 2
9. RAM - 16 GB
10. Performance Insights enabled - Turned on
11. Retention period - 7 days