September 2020 security patch rolled out but there is no MR update. It's really very frustrating.
1) Deny the microphone permission for Google app.
2) open Google app>click on more> select settings>click on voice> click voice match>disable hey google.
3) Now restart the phone.
Don't give microphone permission for Google app in future.
I have no mic issues now.
Note: google assistant can't work with voice.
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