Files seem to be copying to iCloud Drive even though I've not tried to copy anything I opened my icloud drive and noticed a message at the bottom of the Finder window.  The message is shown in the following image.



The way I read this is that 7,546 files and folders totaling 6.29 GB are being written to my icloud drive. Is that correct? If so, why is this happening?  

I am running High Sierra on my iMac.
Apple has gotten ever-more-aggressive about activating iCloud-on-by-default as the years pass.

The most likely cause is that Desktop &amp; Documents iCloud syncing is enabled in System Preferences --> iCloud.

Here are some screen shots, note that in my example I do not have Desktop &amp; Documents syncing turned on.