Idk if they sell your data, but this says they might as well.
Vocal Pitch Monitor - Apps on Google Play
Here's more information the developer has provided about the kinds of data this app may collect and share, and security practices the app may follow. Data practices may vary based on your app version, use, region, and age. Learn more
Apparently that’s boilerplate supplied by Google for anything that uses their ad network, which boost does. That disclosure is mandatory for any country that falls under the GDPR umbrella. There’s a post from the developer explaining this over in the boost sub.