When did "Shut Down" start meaning "Install updates for 45 minutes"?

I still don't understand when clicking "Shut Down" became an invitation to leave my computer busy installing updates for another 45 minutes. Sometimes I finish my work, save everything, and choose to power off, only to discover that Windows has other plans for my evening. I understand that updates are important for security, but forcing them into a normal shutdown makes me wonder why users cannot have more control over when they happen.