Additional meeting and call-related features and issues within Microsoft Teams for Education
I found that deactivating the "Noise supression" option by setting it to "Off" and restarting the teams app no longer forcefully sets my mic volume to 43, i had the problem that my mic sounds fine on 100 and teams always forced it to 43 making me barely audible.
I happened upon the same fix just now, myself. This seems to be the feature that manipulates the mic level.