In case you haven't heard, Apple's upcoming iOS 14 update for iPhone will include a host of opt-in privacy updates that will make it more difficult for companies to track activity on your phone. 

Now, in a blog post, Facebook is warning that these changes will impact the business of developers who rely on the company's Audience Network for ad-driven revenue. 

Facebook's warning is for developers of all stripes, but does include a segment of game developers who rely on in-game ads. A special page branded for gaming promises that Audience Network can "expand the reach of your game's monetization," help you "retain game players" and "drive sustainable growth."

Those three pitches might be rendered moot by Apple's privacy changes. But what's interesting is the change in Audience Network effectiveness isn't entirely controlled by Apple. It will be determined by how many users USE Apple's new privacy features to prevent Facebook from tracking their data.

According to Facebook, "while it’s difficult to quantify the impact to publishers and developers at this point with so many unknowns, in testing we’ve seen more than a 50% drop in Audience Network publisher revenue when personalization was removed from mobile app ad install campaigns," 

Essentially, if enough users opt-out of behavior tracking, it raises the risk that they won't see Audience Network-driven ads, or that the ads won't be relevant. This might lower their effectiveness and therefore, their ability to generate revenue for developers. 

Because of this, Facebook says there may come a time when Audience Network will not be supported on iOS 14.