UI: fix alert flicker when controlsState not updated (#22921)

selfdrive/ui/qt/onroad.cc

@@ -42,10 +42,12 @@ OnroadWindow::OnroadWindow(QWidget *parent) : QWidget(parent) {
 void OnroadWindow::updateState(const UIState &s) {
   QColor bgColor = bg_colors[s.status];
   Alert alert = Alert::get(*(s.sm), s.scene.started_frame);
+  if (s.sm->updated("controlsState") || !alert.equal({})) {
+    alerts->updateAlert(alert, bgColor);
+  }
   if (alert.type == "controlsUnresponsive") {
     bgColor = bg_colors[STATUS_ALERT];
   }
-  alerts->updateAlert(alert, bgColor);
   if (bg != bgColor) {
     // repaint border
     bg = bgColor;