This occurs because the earbuds and the phone use different Bluetooth connection profiles. A2DP (Advanced Audio Distribution Profile) is utilized for high-quality audio streaming, such as music playback, while HFP (Hands-Free Profile) is used for voice calls. The transition between these profiles can sometimes cause the phone to briefly display a connected status followed by a disconnected status. Despite this display change, the functionality of the earbuds remains unaffected. You can continue using them for audio playback and calls without any issues.