Two years ago, Apple and Google each promised a privacy-safe replacement for the device identifiers that mobile marketers had built entire measurement stacks on. The two platforms have landed in opposite places. Apple shipped a system that works and keeps shipping updates to it. Google shelved the one it spent six years building to replace Android measurement, right as marketers were being told to finish migrating onto it.
Google killed the system it told Android marketers to adopt. On October 17, 2025, Google confirmed it was retiring the core of Privacy Sandbox, the six-year effort meant to replace the Android advertising ID. Protected App Signals, the Attribution Reporting API, Topics, and several related APIs are being phased out, according to reporting on the announcement and the Google developer site, which now carries a notice that some Privacy Sandbox technologies are being phased out. Protected App Signals was built specifically for app install attribution and behavioral targeting for the period after the advertising ID disappears. Marketers who spent two years migrating measurement onto it now have to replan.
Apple took the opposite route. AdAttributionKit, which replaced SKAdNetwork, gives advertisers three postback windows, 0 to 48 hours, 2 to 7 days, and 8 to 35 days, instead of one, plus a conversion value range of up to 64 states in its fine-grained tier, according to Apple developer documentation. It is still aggregated and delayed compared with old device-level tracking, but it is a maintained system that ad networks are building against right now.
Users did not punish Apple for asking. Data published by AppsFlyer puts global App Tracking Transparency opt-in at 50 percent as of April 2025, up roughly 10 points since the prompt launched in 2021. iOS non-organic installs grew 29 percent year over year, and iOS ad spend rose 26 percent from 2023 to 2024, both outpacing Android over the same period. The platform that was supposed to be permanently starved of signal is the one advertisers are spending more on. AppsFlyer frames the recovery as users engaging deliberately rather than by default, and the spend numbers back that up.
The practical read for a marketing team: an Android attribution plan built around Protected App Signals or the Attribution Reporting API needs a new foundation, since Google is not maintaining either one, and aggregated, probabilistic modeling is no longer optional on that side. iOS, once the platform everyone complained about, now runs on a published spec with a user base that is increasingly willing to opt in. Budget conversations that still treat Android as the easier platform for attribution are working from an outdated map.
Sources referenced in reporting: Google, Privacy Sandbox Android release notes, CyberInsider, Google Dismantles Privacy Sandbox Core Technologies, Apple, AdAttributionKit developer documentation, AppsFlyer, Market Adaptation to Privacy-First Ecosystem Four Years After ATT.