What should I do if Huawei's mobile phone notification bar is missing?

After upgrading the HarmonyOS system, we distinguish between the notification center and the control center. The notification center is pulled down at the top of the left side of the mobile phone, and the control center is pulled down at the right side.

You can also pull out the notification center or control center page from the top of the screen and slide horizontally in the blank area at the top of the page to quickly switch between the notification center and the control center.