can not assign io1 to eks managed node group attached root volume type

[vagharsh]

i am using the module version : "~> 20.8.5"

this is my configuration :

eks_managed_node_groups = {
   jobs = {
      desired_size = 1
      min_size     = 1
      max_size     = 5
      instance_types = ["m6a.xlarge", "m7a.xlarge", "r6idn.xlarge", "r6in.xlarge", "r5dn.xlarge"]
      capacity_type  = "SPOT"
      ami_type       = "AL2_x86_64"

      block_device_mappings = {
        xvda = {
          device_name = "/dev/xvda"
          ebs = {
            volume_size           = 100
            volume_type           = "io1"
            iops                         = 1000
            encrypted             = true
            kms_key_id            = data.aws_ebs_default_kms_key.current.key_arn
            delete_on_termination = true
          }
        }
      }
    }
}

getting the following error even though i don't have throughput mentioned , i even tried to set it to null but the same result.

│ Error: updating EKS Node Group (dev:jobs-2000000003) version: operation error EKS: UpdateNodegroupVersion, https response error StatusCode: 400, RequestID: xxxxxx, InvalidRequestException: throughput cannot be specified with the volumeType of device '/dev/xvda'
│ 
│   with module.cluster.module.eks.module.eks_managed_node_group["jobs"].aws_eks_node_group.this[0],
│   on .terraform/modules/cluster.eks/modules/eks-managed-node-group/main.tf line 383, in resource "aws_eks_node_group" "this":
│  383: resource "aws_eks_node_group" "this" {
│ 

i was able to launch an EC2 instance with the same type and attach io1 volume with 100GB and 1000 IOPS as root volume block mounted to /dev/xvda

if i change the io1 to gp3 and add the throughput it works fine but not with io1
could someone shed some light on the secret recipe here ?