OP should clean both microphones on their phone, usually a sewing needle or thin toothpick can do the trick, but 99% Isopropyl on a toothbrush might be needed afterwards if the grill inside that protects the microphone is also clogged up.

Both microphones need to be cleaned of any blockages so the hardware echo and noise cancellation on a given phone works well. Otherwise you've got distorted audio getting processed as if it's not distorted...