The long-awaited privacy update to Apple’s iPhone and iPad operating systems that could dramatically hurt mobile advertising is coming in “early spring,” Apple told CNBC on Wednesday.

To target mobile ads and measure how effective they are, app developers and other industry players currently often use Apple’s (IDFA), or a string of letters and numbers that’s different on every Apple device. But once this update rolls out, app makers will be forced to ask permission to access a user’s IDFA through a prompt. A significant portion of users are expected to say no, reducing the effectiveness of targeted ads.

Apple first announced the change last summer, giving advertisers and app makers ample time to prepare. But it’s become a major point of contention for ad-supported companies, who could lose revenue from the change.

Facebook in particular argues that the change will hurt the availability of free content on the open web and the ability of small business to place personalized ads. On Facebook’s Q4 2020 earnings call Wednesday, CEO Mark Zuckerberg slammed the change, calling Apple one of its biggest competitors and claiming that the change “threatens the personalized ads that millions of small businesses rely on to find and reach customers.” 

The timing of Apple’s change has been the subject of intense speculation in the mobile industry. Apple CEO Tim Cook is set to speak Thursday about data privacy at the Computers, Privacy and Data Protection conference in Brussels. On Thursday, the company is also releasing new marketing materials, including an update to its website and a report on data usage to illustrate how companies track user data across websites and apps.

Apple told CNBC that the next beta version of iOS will require app developers to ask permission to access the phone’s unique identifier.

The current version of iOS is 14.4, which was released earlier this week. There currently isn’t a public