18,000 Android apps with tens of millions of installs on Google Play Store violate Google’s Play Store Advertising ID policy guidance by sending persistent device identifiers such as serial numbers, IMEI, WiFi MAC addresses, SIM card serial numbers to mobile advertising related domains. Google did not yet respond to a report sent by AppCensus in September 2018 containing a list of 17,000 apps that send persistent identifiers together with ad IDs to various advertising networks. Google said in a statement sent to CNET that “We take these issues very seriously”””
Source: https://www.bleepingcomputer.com/news/security/18-000-android-apps-track-users-by-violating-advertising-id-policies/