Why does the receiver sound low when holding the POCO F7 Ultra during calling mode?

It is recommended that you check whether the phone's film, leather case, etc., are blocking the receiver. If so, please remove them and try again.
Also, check whether the receiver is dusty or blocked by foreign objects. It is recommended that you use the volume up button to increase the volume during a call and confirm the volume.
In addition, you can try to adjust the position of the receiver next to your ear to get a louder sound or switch between left and right hands when you feel the sound is low. This will have a better effect. Thank you for your support.