Google Play Protect is meant to keep nefarious apps off users' devices. Alternative app marketplace Aptoide has been flagged as such an app, according to a complaint the company has filed with the European Commission. Play Protect is reportedly cautioning some users that Aptoide is potentially harmful, and preventing the store from downloading apps for those who don't heed the warning.

Aptoide CEO Paulo Trezentos has said that the store is one of the safest on Android, criticizing the Play Protect warnings as "really aggressive." Google hasn't commented on the complaint.

Google has already had antitrust troubles in Europe, where it was fined $2.7 billion last year for prioritizing its own shopping service above competitors' in search results. The company could soon face additional fines in the billions of dollars for pushing users to use its own services like Chrome and Google Search over competing ones such as Firefox or Yahoo; prioritizing the Play Store over alternatives like Aptoide could be seen as a similar move.