Amazon ECS capacity provider is not scaling out instance at target_capacity=100

I have enabled ECS to use capacity provider, here is my configuration details

• Auto-scaling for ECS task min=2, desired=2, max=8 and auto-scaling policy for this tracks CPU utilization at 10%(for validation if task are scaling out and in)
• Auto-scaling group for Capacity-provider with min=1, desired=2, max=4

Initially after deployment 2 ECS task were running on 2 different EC2 instance, then I ran load test to verify if Cluster and ECS task scales as expected but ECS task desired count was changed to 8 and only 4 ECS task were running(which is expected as there are 2 EC2 instance and I use t3.medium(3 ENI) instance with AWSVPC for my deployment ).

Why did the cluster did not scale as there are already 4 task which are in provisioning state capacity provider threshold is at 100?

I'm using terraform to deploy my infrastructure and details for capacity provider is as below,

resource "aws_autoscaling_group" "kong" {
  ...
  min_size             = var.asg_min_size
  max_size             = var.asg_max_size
  desired_capacity     = var.asg_desired_capacity
  protect_from_scale_in = true
  tags = [
    {
      "key"                 = "Name"
      "value"               = local.name
      "propagate_at_launch" = true
    },
    {
      "key"                 = "AmazonECSManaged"
      "value"               = ""
      "propagate_at_launch" = true 
    }
  ]
}

resource "aws_ecs_capacity_provider" "capacity_provider" {
   name = local.name

   auto_scaling_group_provider {
      auto_scaling_group_arn         = aws_autoscaling_group.kong.arn
      managed_termination_protection = "ENABLED"

      managed_scaling {
           maximum_scaling_step_size = 4
           minimum_scaling_step_size = 1
           status                    = "ENABLED"
           target_capacity           = 100
      }
   }

  
   provisioner "local-exec" {
      when = destroy

      command = "aws ecs put-cluster-capacity-providers --cluster ${self.name} --capacity-providers [] --default-capacity-provider-strategy []"
   }
}

resource "aws_ecs_cluster" "kong-reg-proxy" {
  name      = local.name
  capacity_providers = [
    aws_ecs_capacity_provider.capacity_provider.name,
  ]
  tags = merge(
    {
      "Name"        = local.name,
      "Environment" = var.environment,
      "Description" = var.description,
      "Service"     = var.service,
    },
    var.tags
  )
}