Google has a policy against targeting ads at minors, but it’s been caught slipping. A report by The Financial Times alleges that employees at the company teamed up with Meta to use a loophole that let them run YouTube ads selling Instagram to teenagers.

According to the publication, the ads were served to users labeled as “unknown” in Google’s systems, which is supposed to refer to users whose age, gender, parental status, and household income are, well, not known. Unfortunately for Google, the publication found that Google could use app downloads and other activity to know “with a high degree of confidence” that the unknown group is overwhelmingly populated by teenagers.

The report goes on to claim that Google employees have been using the unknown group as a loophole to target ads at teens without technically breaking their company’s policies. When the publication approached Google with its findings, the company pulled the campaign, undoing plans to take it abroad after launching it in Canada and trialing it in the United States.

“We prohibit ads being personalized to people under 18, period,” Google told FT, saying it would be launching an investigation into attempts to circumvent its rules. “We’ll also be taking additional action to reinforce with sales representatives that they must not help advertisers or agencies run campaigns attempting to work around our policies.”

The search giant also tried to lessen the damage in a statement to Quartz, where it said the campaign was “small in nature.”

While the campaign only broke internal policy as opposed to any (current) laws, news of the loophole comes amidst serious legal scrutiny on how companies use children’s data online. Last month, the U.S. Senate passed a bill that would ban targeted advertising to minors as well as nonconsensual collection of their data. Additionally, the U.S. Department of Justice sued TikTok just last week for illegally collecting data on users under the age of 13 without parental consent.