https://www.cityfreqs.com.au/pilfer.php
PilferShush is an experimental F-droid app that is supposed to prevent this kind of tracking by blocking your phone's microphone and jamming the Audio frequencies used for tracking. F-droid page:
https://f-droid.org/en/packages/cityfreqs.com.pilfershushjam...
Edit: Wikipedia says there are 234 android apps that use ultrasound audio tracking, but the article it references is from 2017 and behind a paywall...
https://en.wikipedia.org/wiki/Cross-device_tracking#Applicat...