I had something odd happen a few days ago - saw the 'there are new updates' pop up on the taskbar, and clicked the X to make it disappear ...next thing I know, it's downloading updates! I stopped it and thought no more until shut-down that night, and it installed the ones it had managed to download.
I'm reluctant to even look at the updates in case it auto downloads more of them!
From what I can see on the drive, it was mostly .NET updates.
I remember some people getting W10 downloading when they clicked X on the window to close it!