By pausing IDFA collection, Facebook will effectively halt serving personalized in-app ads to iPhone users once they upgrade to iOS 14, an update that is expected as soon as next month and likely to have far-reaching implications for the industry.

The move will “disproportionately affect Audience Network,” the social network’s ad network for app developers, with Facebook claiming the pending update from Apple may render the network so ineffective that it “may not make sense to offer it on iOS 14.”

Sources told Adweek the social network informed publishers to expect up to a 50% reduction in ad revenue from Audience Network in the days running up to the announcement.

Facebook claimed the iOS 14 updates will have “less impact” on its own advertising business, although its ability to serve personalized in-app ads to iPhone users will undoubtedly be diminished, with measurement providers also likely to be impacted.

“The new version of the Facebook SDK [software development kit] will provide support for Apple’s SKAdNetwork API, which limits the data available to businesses for running and measuring campaigns,” reads a blog post detailing the changes.

“In light of these limitations, and in an effort to mitigate the impact on the efficacy of app-install campaign measurement, we will also ask businesses to create a new ad account dedicated to running app install ad campaigns for iOS 14 users.”

Alex Austin, CEO of user measurement firm Branch Metrics, told Adweek the announcement was an ominous sign for Facebook’s ad network and could mean Apple’s iOS 14 update is incompatible with the ad-funded app ecosystem.

“The potential death of Facebook Audience Network is just the first sign of the impending apocalypse on the advertising-funded app economy,” he added. “Apple’s move has gone too far, disproportionately disrupting a vibrant app ecosystem by throwing the baby out with the bathwater.”