https://www.pcgamer.com/task-manager-bug-in-windows-10-october-update-misreports-cpu-usage/

For the past couple of days, Microsoft has been rolling out its October 2018 Update for Windows 10, the last of two major upgrades planned for this year. I installed it on my own PC without any major issues. However, I can confirm reports that a previously known Task Manager bug has hitched a ride with the final release.

A user on Reddit noted that the Task Manager is not showing the correct CPU usage after updating Windows.