Original post by: Nicolás Ibáñez ,
Google Pixel has three different microphones. The main one located next to the USB-C charging port is used for making calls and voice commands. The "camcorder mic" is independant, so perhaps it is malfunctioning (Google is replacing phones because of this, is a known factory issue). Did you try sending the video to another device and watch it there? Is the video without audio or your device fails to play the audio of that video in particular?