https://www.theregister.co.uk/2019/06/04/scareware_ads_windows_store/

Application makers are crying foul after some of their programs distributed via the Windows Store pops open tech-support scam ads on users' desktops.

A thread in Microsoft's support forum, active since April 28, details the scandal: programmers who use Redmond's Advertising Software Development Kit (SDK) to display ads in their apps, available via the Windows Store, to generate revenue say bad banners are being forced open in their users' browsers.