Why is my Mac Studio microphone not working on Google Chat?

It appears that your Mac Studio may have defaulted to using your iPhone's microphone after it was connected via USB for Personal Hotspot, and now it's "stuck" prioritizing that over your Studio Display’s mic. This is somewhat of a common issue when Apple devices auto-switch input/output sources after detecting new ones — especially when an iPhone is connected with "Continuity Camera" or "Handoff"-related features.

I suggest starting by verifying the current microphone input priority on your Mac.

1. Open System Settings > Sound
2. Under Input, check what microphone is currently selected. If your Studio Display is listed there, manually select it. Speak and watch the input level meter — it should move.

Now, let's check it in Google Chat.

1. While in a Google Chat call, click the three-dot menu (⋮) and go to Settings > Audio.
2. Make sure Microphone is set to “Studio Display”.
3. Test it within the browser’s sound input selector.

If that didn't help, something else you can try is to revoke the iPhone's microphone pemissions.

1. Go to System Settings > General > AirPlay & Handoff
2. Disable Continuity Camera if it's enabled.
3. Unplug the iPhone and restart the Mac Studio to fully clear that default route.

Finally, try resetting the microphone input order.

1. Disconnect the iPhone.
2. Go to Audio MIDI Setup (in Applications > Utilities).
3. Select the Studio Display and ensure it’s not muted or set to zero input volume. You can also create a new “Aggregate Device” if macOS is being stubborn and not prioritizing the Studio Display.

You're very welcome!

Hmm. At this point, I suggest that you contact Apple Support directly for assistance with this issue. To do so, simply select the "Support" link on the lower left-hand side of this forum's web page.