try the Water Eject shortcut. If your iphone got water damage or water stuck inside like what I experience before during rain time, water damage the mic. That moment i was thinking to send to service centre for warranty claim, but luckily found this Shortcut ''water eject'', its actually using sound wave to push the water out of your phone and everything works normally after the ejection process.

once I got my phone under the rain and it actually makes the speaker came out those sound like fireworks. But it actually solved by using this method once after the process finished.