Audio from the front camera's video keeps changing volume level
Audio from the front camera's video keeps changing volume level. At the start of the video, the audio is just fine then after a second the audio suddenly sounds muffled and you can really hear the sudden change of the volume from high to low. But when I use a 3rd part app to record video like Instagram, the audio is just fine. Maybe this is a software issue? I really need some help guys.
iPhone 6s, iOS 11.2.5