Why can’t the Xiaomi Smart Band 8 be found when paired and connected with a new phone after unilaterally restoring it to factory settings?

Check as follows:
The iOS mobile phone is connected to the device, and after the device is unilaterally restored to the factory, the Bluetooth of the iOS mobile phone system will try to connect back to the device, and the new mobile phone may not be found ((The iOS mobile phone and the device will always be disconnected, and the new mobile phone cannot be found during the connection period; In the gap between the breaks, the new phone is just in the scanning state and can be searched)). You need to enter the Bluetooth of the iOS mobile phone system, find the corresponding connected device, and ignore this device. At this time, use the new mobile phone to search for pairing connection.
The Android phone is connected to the device. After the device is unilaterally restored to the factory, the Mi Fitness App will connect back to the device and prompt the user that the current "Delete" is still "Add". At this time, the new phone cannot search for the device. Click "Delete", and then use the new mobile phone to search and connect.