Due to the iOS platform-related reasons, when this issue occurs, please try to restore it by following the steps below:
1. Open the Settings app on your phone, go to the Bluetooth interface, and check if the Earbuds device is among the connected devices. If it is, tap the "i" button next to the Earbuds and then select "Forget This Device".
2. Re-enter the Nothing X App and re-perform the pairing and connection process.