Apple’s ad tracking transparency (ATT) feature is set to officially launch in “early spring.” And over the previous months, Facebook has been the biggest critic of the impending changes. Ahead of the new iOS privacy requirement, EU antitrust chief Margrethe Vestager has said it does look to line up with some of the proposed legislation in Europe but also gave a warning for Apple to play fair.

Reported by Reuters, Vestager said for now she hasn’t gotten any official complaints about Apple’s upcoming ad tracking transparency feature. It will give iPhone and iPad users a warning when apps and websites are tracking them with an easy way to opt-out with a tap.

Vestager said that the feature looks to be in line with the EU’s recently proposed Digital Services/Markets Act legislation.

However, she also gave a general warning that it could go beyond the user privacy focus and become anticompetitive:

“It is a very good thing to have a clear opt-out option. If you look at the Digital Services Act, the Digital Markets Act, these are some of the solutions we are looking at there.”

Facebook is planning an antitrust lawsuit against Apple over the ATT feature. But that may be an uphill battle for Facebook as Apple is really just giving users choice whether or not to allow app and website tracking.

“It can be competition if it is shown that Apple is not treating its own apps in the same way,” she told Reuters in an interview on Monday.

Apple has said the the ATT feature will apply to itself as well as all third-party developers. There were similar concerns about how Apple would treat its own apps when the company launched its privacy nutrition labels for app. But it hasn’t been an issue as it launched a website to detail its privacy practices for any of its own apps not on the App Store.