Windows 10's December update, patch KB5071546, has caused various issues for users, including a blank screen on some PCs, performance problems like choppy wallpaper animations and CPU spikes, and lag in the user interface. Gamers have reported frame rate drops in games like Overwatch and issues with the Xbox app. Users with dual-monitor setups have experienced failures in their displays, and some have faced difficulties with the update failing to install. A potential solution for the StartIsBack application issue is to install its latest version, although this may require removing the existing version. The update includes a security fix for PowerShell 5.1, but users must consider the risks of remaining on an older version due to potential vulnerabilities.