Microsoft has started inserting advertising into its Bing Wallpaper app for Windows, replacing users' usual rotation of scenic desktop images with a promotion for a Harry Potter and Fantastic Beasts film collection. The change, which appeared on Monday, has prompted complaints on Reddit and Microsoft's own Learn support forum, with users asking why their wallpaper had been hijacked and whether there is any way to opt out. It marks a further step in Microsoft's ongoing practice of embedding promotional content into core parts of Windows, following earlier moves such as ads in the Start menu.

The wallpaper shows a vector-style image of Hogwarts castle alongside text advertising the "11-film collection", with all eleven Harry Potter and Fantastic Beasts films described as "available now". Numerous one-star reviews have appeared on the app's Microsoft Store page, with users objecting simply to the presence of adverts rather than to author J.K. Rowling's politics, and some noting that the app's settings now disclose the use of AI-generated wallpapers. This is not the app's first controversy: in late 2024 it was found to be accessing and decrypting browser cookies, which Microsoft did not fully deny. Microsoft did not immediately respond to a request for comment, and affected users are being advised that uninstalling the app is currently the only way to avoid the adverts.