Why is my rear microphone making hissing/static noise?

My iPhone 8 Plus, when taking videos with the main (rear) camera, just outputs static sounding hissing noise over the entire audio. This suddenly started happening a week ago; before then the audio was clear. Front camera audio is fine, and voice memos audio is fine as well. It’s just the rear microphone. I tried cleaning the mic, and it’s perfect on the outside, but the hissing has only gotten worse. I can still hear some audio, but the incessant hissing ruins everything.

It sounded to me like a hardware issue with the rear microphone. However, I can’t find what part this microphone is attached to, not how to replace it. It doesn’t seem to be attached to the rear dual camera part (thank God, because it’s expensive). So what part do I need to fix this microphone?