This is latest recommended approach from GCP docs here: https://cloud.google.com/run/docs/authenticating/public#terraform

resource "google_cloud_run_service_iam_binding" "default" {
  location = google_cloud_run_v2_service.default.location
  service  = google_cloud_run_v2_service.default.name
  role     = "roles/run.invoker"
  members = [
    "allUsers"
  ]
}