iPhone XR Microphone does not work properly when using Phone app

This is an interesting bug. The microphone on my iPhone XR does not work properly when using the Phone app. This iPhone XR is running iOS 17.5.1 (21F90).

Context: When I call someone or someone calls me, they cannot hear me or will only hear muffled voices. They can only hear me when I put my phone on Speaker mode, and hear muffled/unclear voice in regular mode.

Other apps v. Phone app: I’ve tested the microphone on other apps like VoiceMemo, camera (video recording), WhatsApp, etc. and the microphone works well in all these apps. It works properly and folks receiving my calls are able to hear me if I use WhatsApp in regular/non-speaker mode.

This issue only seems to exist in the Phone app.

What I’ve tried: I’ve already tried restarting the phone a few times and this hasn’t helped. I’ve also tried turning off Bluetooth, and this hasn’t helped either.

Any thoughts or suggestions on what else I can do?

Thanks for your time!