Changing name setting in version block triggers an update on the "google compute region instance group manager" resource

Terraform
1

Hi there,

We have created a managed instance group using the below configuration

resource "google_compute_region_instance_group_manager" "gui" {
  name = join("-", [var.cluster_name, "guinode-mig"])

  base_instance_name        = join("-", [var.cluster_name, "guinode"])
  region                    = var.region
  distribution_policy_zones = [var.zone]

  version {
    instance_template  = google_compute_instance_template.gui.self_link
  }

  target_size  = 1

  named_port {
    name = "httpsport"
    port = 8443
  }
}

It can be seen that the version block doesn’t have any value for the name setting. But after a few terraform apply operations, the plan started to show that the google_compute_region_instance_group_manager resource is going to be updated because of the changing value of the name. The output is shown below:

# module.redacted.google_compute_region_instance_group_manager.gui will be updated in-place
 ~ resource "google_compute_region_instance_group_manager" "gui" {
        base_instance_name        = "redacted"
        distribution_policy_zones = [
            "us-west2-c",
        ]
        fingerprint               = "redacted"
        id                        = "redacted"
        instance_group            = "redacted"
        name                      = "redacted"
        project                   = "redacted"
        region                    = "redacted"
        self_link                 = "redacted"
        target_pools              = []
        target_size               = 1
        wait_for_instances        = false

        named_port {
            name = "redacted"
            port = redacted
        }

        update_policy {
            instance_redistribution_type = "PROACTIVE"
            max_surge_fixed              = 1
            max_surge_percent            = 0
            max_unavailable_fixed        = 1
            max_unavailable_percent      = 0
            min_ready_sec                = 0
            minimal_action               = "RESTART"
            type                         = "PROACTIVE"
        }

      ~ version {
            instance_template = "redacted"
          - name              = "0-1624390439185" -> null
        }
     }

Since the file that contains the configuration for google_compute_region_instance_group_manager resource has not been changed, I have difficulty understanding why this kind of update is triggered. Would there be any explanation so that I can avoid these kinds of changes? By the way, I assume that I can avoid this by setting the name explicitly but knowing the exact reason would be nice.

Thanks in advance,

Ender