https://www.bleepingcomputer.com/news/microsoft/final-windows-7-update-breaks-desktop-wallpaper-functionality/

The final update for the Windows 7 operating system has broken some of the desktop wallpaper functionality and caused user's backgrounds to become a blank black screen.

On January 14th, 2020, Windows 7 reached its End of Life, which means there will be no more bug fixes or free security updates past that date.