Tech giants Google and Meta collaborated on a marketing project to target YouTube users aged 13 to 17 with Instagram ads, skirting Google’s own rules for treating minors online.

Documents reviewed by the Financial Times reveal that Google worked with Mark Zuckerberg’s Meta to target a group of YouTube users labeled as “unknown” in its advertising system, which skewed towards under-18s. This project disregarded Google’s policies prohibiting personalized ads for minors.

The collaboration between the two companies, usually fierce competitors, began late last year. Google aimed to boost advertising earnings, while Meta sought to retain younger users against rivals like TikTok. Spark Foundry, a subsidiary of French advertising giant Publicis, developed the project. It was piloted in Canada between February and April this year and trialed in the U.S. in May.

Google saw these pilots as a chance to establish a more lucrative relationship with Meta, involving expensive “brand” adverts on YouTube and other platforms. However, when contacted by the Financial Times, Google initiated an investigation into the allegations, and the project has since been canceled.

Google stated it prohibits personalizing ads to people under 18 and that its policies are supported by technical safeguards. However, it did not deny using the “unknown” loophole to target users without explicitly identifying them as minors.

Meta contended that targeting the “unknown” audience did not constitute personalization or rule circumvention, claiming it adhered to its own policies and industry standards. Meta has faced scrutiny over its policies on minors, with ongoing lawsuits and investigations by the Federal Trade Commission. In 2021, the company shelved plans to launch a kids version of Instagram following public backlash and leaked research suggesting the app harms teenage girls’ mental health.