ITMS-90683: Missing purpose string in Info.plist

I have an app that is getting rejected from TestFlight because of this error:

ITMS-90683: Missing purpose string in Info.plist - Your app’s code references one or more APIs that access sensitive user data, or the app has one or more entitlements that permit such access. The Info.plist file for the “TurtleTuner.app” bundle should contain a NSCameraUsageDescription key with a user-facing purpose string explaining clearly and completely why your app needs the data. If you’re using external libraries or SDKs, they may reference APIs that require a purpose string. While your app might not use these APIs, a purpose string is still required. For details, visit: https://developer.apple.com/documentation/uikit/protecting_the_user_s_privacy/requesting_access_to_protected_resources.

The app does not use the camera, only the microphone. I cannot find references to the camera in any of the third party libraries I'm using.

What are some ways to troubleshoot this beyond looking for "camera" in the few dependencies?

For context, this commit allows the app to get through successfully to TestFlight: https://github.com/tsargent/turtle-tuner/commit/67d4a52e62839ad6c2a49848bea9c408d983f17a

While this following commit, which reverts the commit, fails on TestFlight with the mentioned camera permission error: https://github.com/tsargent/turtle-tuner/commit/c95b0b16c4e85d77e625d36b816ed53faa826cf5