As you noted, this is likely due to your ECS workload. Config records every change to your environment. If you are using VPC Networkring mode, this would explain the high number of networking items being recorded in Config. From: From https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task-networking.html
awsvpc — The task is allocated its own elastic network interface (ENI) and a primary private IPv4 address. This gives the task the same networking properties as Amazon EC2 instances.
So you can see if you have a high volume of containers being spawned/removed, this will contribute to the high volume of Config items being recorded. Also there are relationships in Config which explains the other networking items like subnet, security group, etc. See https://docs.aws.amazon.com/config/latest/developerguide/faq.html
As to why it suddenly happened, were any changes made to config or config recorder? Was Control Tower deployed recently? That would enable the config recorder in all governed accounts.
Lastly, check out this post which gives some further info and suggestions https://repost.aws/questions/QUw4fCo698SxKa0zy5uh17Wg/how-to-turn-off-aws-config-and-reduce-cost
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Thanks for your reply!
I noticed that the tasks was allocated with awsvpc, make sense.
I'm worry too about the cost increase, in March it's about $20, and April and May, exceeded $300.
Control Tower was not deployed, CloudWatch Container Inisghts, can do this?
No its not Container Insights. Looks like config has always been enabled and the cost is directly related to your ECS activity and task count as you've shown in your graphs. You can see every spike in task count corresponds to a spike in config costs. You can change the config recorder to filter out the resources that you don't need or want to record depending on your requirements. See https://docs.aws.amazon.com/config/latest/developerguide/select-resources.html
I think that I found it!
I got the service's PendingTaskCount and RunningTaskCount metrics, I found a task that frequently change status (pending to running, to pending...).
Coincidentally these changes, correspond to the days with most cost. The recently logs prove this theory too, the task changes many times a day. What do you think?