I got into an issue that my microphone is not working during calls but it's working fine with Google assistant. People in the other side couldn't hear me but I can hear them. But this is not an issue anymore at speaker mode or when I am using a headset.
Also the issue is avoidable when I cover the phone with hand and talk during the call or if I directly talk through the microphone by placing the phone horizontally near the mouth.
Is it hardware issue or a software issue?