Along with some pretty cool new features in Windows 10, Microsoft introduced one that's more annoying than cool: the ability to inject ads for its own products directly into the operating system. Yes, now you can see ads in Windows applications and the Windows Store app, not just on web pages.
The latest of these is an ad in the Windows File Explorer to upgrade Microsoft's OneDrive cloud storage service. An article on DigitalTrends.com provides instructions for turning off the ad. Note, however, that if you use OneDrive you may also miss out on some potentially important notifications.
Browser-based ad blockers such as AdBlock can't see these ads because they're part of the Windows operating system itself. That means AdBlock can't block them. It also means that even using a host file or a VPN won't prevent them from appearing in Windows applications. It looks as if Windows 10 users are stuck with the ads until Microsoft decides to stop pushing its products this way.