Try running a Teams meeting test in the Settings menu under Devices. Get close to the Mic and talk as loud as you can, if it plays back as a very low voice then what you are experiencing is a Driver issue
not a Windows Teams issue. You will need to contact the the hardware provider (Dell, Lenovo, etc...) it would be an issue they need to fix.
This isn't the case for me. Zoom, join.me, etc all work with expected volumes (I'm using a logitec headset). When using Teams, and ONLY Teams, the volume is extremely low. For me, this is an app issue, not a driver issue. If other apps are working as expected,
then so should Teams...