Azurerm_application_gateway keep on updating without any changes in configuration

azurerm_application_gateway still updating for almost 2hr without any modification in the configuration.

resource "azurerm_application_gateway" "twistlock_app_gw" {

  name                = local.app_gateway_name

  resource_group_name = data.azurerm_resource_group.rg.name

  location            = data.azurerm_resource_group.rg.location

  sku {

    name     = var.app_gateway_sku

    tier     = "WAF_v2"

    capacity = 1

  }

  waf_configuration{

    enabled = "true"

    rule_set_type    = "OWASP"

    rule_set_version = "3.1"

    firewall_mode = "Prevention"

  }

  gateway_ip_configuration {

    name      = var.gateway_ip_configuration_name

    subnet_id = azurerm_subnet.subnet_agw.id

  }

  frontend_port {

    name = local.frontend_port_name

    port = 80

  }

  frontend_port {

    name = "httpsPort"

    port = 443

  }

  frontend_ip_configuration {

    name                 = local.frontend_ip_configuration_name

    public_ip_address_id = azurerm_public_ip.agw_public_ip.id

  }

  backend_address_pool {

    name = local.backend_address_pool_name

  }

  backend_http_settings {

    name                  = local.http_setting_name

    cookie_based_affinity = "Disabled"

    port                  = 80

    protocol              = "Http"

    request_timeout       = 1

  }

  http_listener {

    name                           = local.listener_name

    frontend_ip_configuration_name = local.frontend_ip_configuration_name

    frontend_port_name             = local.frontend_port_name

    protocol                       = "Http"

  }

  request_routing_rule {

    name                       = local.request_routing_rule_name

    rule_type                  = "Basic"

    http_listener_name         = local.listener_name

    backend_address_pool_name  = local.backend_address_pool_name

    backend_http_settings_name = local.http_setting_name

  }

  tags = {

    environment = var.environment

  }
}