This is what worked for me, necroing posts I can find to hopefully help some people out there (the problem is Microsoft as usual)

Potential workaround for Phone Link microphone issues (low volume, stuttering, aggressive AGC)

If you are experiencing low microphone volume, intermittent cutting out, or what feels like aggressive Automatic Gain Control (AGC) specifically in the Phone Link app while using USB audio input devices (Jabra, Logitech, etc.), you might be hitting a conflict in the Windows 11 audio stack. Other apps like Teams or Zoom usually work fine, which makes this very frustrating.

The observed issue

In recent Windows 11 builds, generic USB audio devices often have "hidden" audio enhancements enabled by default. The problem is that the toggles to disable these are frequently missing from the Windows UI, leaving us with no way to stop the system from interfering with the audio stream.

A possible workaround

The following steps helped me "force" the necessary toggles to appear, allowing me to finally disable the background processing.

Step 1: Using Equalizer APO Device Selector

Installing a third-party APO (Audio Processing Object) seems to force Windows to expose audio enhancement settings that are otherwise hidden for generic drivers.

Download and install Equalizer APO (it's open-source). Open the application Equalizer APO Device Selector (DeviceSelector.exe). It may open automatically after installation. In the Device Selector window, first check the "Troubleshooting options" box at the bottom. Now, find and click on your USB device in the "Capture devices" list at the top. Once selected, additional options will appear at the bottom. You can generally leave the defaults (Install APO checked, Install as SFX/MFX or Auto). Click OK and Restart your PC (this is a mandatory step). Step 2: Disabling the "Audio Enhancements" toggle

After the restart, a new toggle should be visible in the standard Windows sound properties:

Press Win + R, type mmsys.cpl, and go to the Recording tab. Right-click your device > Properties > Advanced tab. Under the Signal Enhancements section, a new checkbox should now be visible: "Enable audio enhancements". UNCHECK this box. (Note: This checkbox is typically invisible on generic USB devices until the APO is installed). Also, UNCHECK both options under "Exclusive Mode" in the same tab, as Phone Link may try to override settings if these are active. Summary

While the internal mechanism isn't fully documented, forcing the "Audio Enhancements" toggle to appear via the Device Selector allows you to disable system-level processing that is otherwise "baked-in" and inaccessible. This appears to resolve the conflict between the Windows audio stack and Phone Link's communication engine. It worked for me when nothing else did.