How to trigger an AWS Event Rule when a S3 key with a specific suffix gets uploaded

I'm trying to create an AWS Event Rule that is only triggered when a file with a specific suffix is uploaded to an S3 bucket.

{
  "source": [
    "aws.s3"
  ],
  "detail-type": [
    "AWS API Call via CloudTrail"
  ],
  "detail": {
    "eventSource": [
      "s3.amazonaws.com"
    ],
    "eventName": [
      "PutObject",
      "CompleteMultipartUpload"
    ],
    "requestParameters": {
      "bucketName": [
        "bucket-name"
      ],
      "key": [
        { "suffix": ".csv" }
      ]
    }
  }
}

As I understand there AWS has content-based filtering which can be used but docs doesn't show the ability to use a suffix, only prefix among other patterns: https://docs.aws.amazon.com/eventbridge/latest/userguide/content-filtering-with-event-patterns.html

Ideally I could be able to do it here without the need for an intermediary Lambda as my event target is an ECS Fargate task.

It appears that suffix matching has been added

https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-event-patterns-content-based-filtering.html#eb-filtering-suffix-matching

Therefore, the example given in the question is now valid!