Dynamic subnet names aren't being assigned

[talorlik]

Description

This line: format("${var.name}-${var.private_subnet_suffix}-%s", element(var.azs, count.index)) doesn't assign the names correctly even though the var.private_subnet_suffix has been assigned. It only takes the name of the VPC and that's it.

• ✋ I have searched the open/closed issues and my issue is not listed.

Versions

• Module version [Required]: 5.17.0
• Terraform version: v1.9.8
• Provider version(s): v5.82.2

Reproduction Code [Required]

module "vpc" {
  source  = "terraform-aws-modules/vpc/aws"
  version = "5.17.0"
  name    = local.vpc_name
  cidr    = var.vpc_cidr
  azs     = local.azs
  private_subnets = flatten([
    for k, v in local.azs : [
      cidrsubnet(var.vpc_cidr, 4, k * 2),
      cidrsubnet(var.vpc_cidr, 4, k * 2 + 1)
    ]
  ])
  private_subnet_suffix = "subnet"

  create_database_subnet_group  = false
  manage_default_network_acl    = false
  manage_default_route_table    = false
  manage_default_security_group = false

  enable_dns_hostnames = true
  enable_dns_support   = true

  enable_dhcp_options      = true
  dhcp_options_domain_name = "${var.region}.compute.internal"

  single_nat_gateway     = true
  create_igw             = false
  create_egress_only_igw = false

  private_route_table_tags = {
    Name = local.route_table_name
  }
  tags = {
    Name = local.vpc_name
  }
}

Expected behavior

I'd expect the names of the 4 subnets, 2 in each AZ to be as follows (in my case):

• vpc-qa-subnet-1
• vpc-qa-subnet-2
• vpc-qa-subnet-3
• vpc-qa-subnet-4

Actual behavior

• vpc-qa
• vpc-qa
• vpc-qa
• vpc-qa

If this can please be sorted out that would be highly appreciated.

Regards,