Ensure the user is in an area with good connection and the problem is only happeing with headphones on.                                                                     "

Cellular: The Headset mic is futher away than a TWS mic, which may cause slightly less voice quality over calls, this is a factor that needs to be accepted                                                                                           

 Online : Change network/ Wi-Fi and check still issue persist check internet speed and Reset Post that if issue persist go for RPU."    The Mic is further away from the users mouth than a typical TWS thus the mic will pick less voice

The Mic is further away from the users mouth than a typical TWS thus the mic will pick less voice