"Mobile device advertising ID (IDFA for iOS devices, Android Advertising ID for Android devices), Unique device identifiers (e.g., IMEI, MAC address). We may also share your online activity or device information with marketing partners to promote our products and services."
Collection of advertising IDs (IDFA, Android Ad ID) and persistent hardware identifiers (IMEI, MAC address), combined with sharing this data with marketing partners, enables cross-app and cross-service tracking of users.