Linking Photos to iCloud bloats source file size
When I change Photo preferences in my MacBook Pro to "iCloud photos...automatically upload and store..." I get the message "Your full-resolution photos and videos stored in iCloud may not fit on this Mac. The library on this Mac can be optimised to take up less space. All your full-resolution originals will be stored in iCloud and accessible in the Photos app. Time Machine will no longer back up all full-resolution originals."
I do not want reductions in the Photos library on my BacBook, I simply want the Photo library on my MacBook to be copied to the Cloud. Copying to the cloud cannot increase the the size of the source Photos database. How do I fix this. My Photos folder on iCloud does have images in it that have been uploaded from other sources (like my phone): is the Mac trying to sync these back to the MacBook (without any instruction to do so)?
Catalina 10.15.6 MacBook Pro quad i7
MacBook Pro 15″, macOS 10.15