Why do the red dots (notifications sent by APPs) disappear after opening corresponding APPs in the Xiaomi smartphone?

Notifications sent by APPs can take various forms, depending on the platform, the type of APP, and the specific notification system used.
Thank you for your feedback. This is a normal phenomenon. The system cannot determine whether the notification within the APP has been read. It will only display a red dot prompt when a notification comes in, which does not affect your use.