You have turned on iCloud Drive and desktops and documents box , if you uncheck the box of desktops and documents the files / personal documents will be temporarily un-synced but they still occupy iCloud space .
It will prompt the items from this desktop and the documents folder are available in iCloud Drive , to remove items from iCloud Drive , move them to your desktop and documents folder on this Mac , click on show in finder .
Again open system preferences > iCloud > iCloud Drive > the box of desktops and documents box is unchecked , tap over the box to get it rechecked , a circle rotates setting up the box gets checked .
You will notice a folder is created literally on the desktop , tap it a pop up window appears the items on this desktop on this Mac have been moved into a new folder called “ Desktops - Apples Mac book …( the name of Mac will be written in the existing desktop folder in iCloud Drive , you can combine the contents of these folders any time , click on show in finder .
Right click on the folder created on the Mac and move to trash , restart the Mac and empty the trash , but again the documents are placed in a right place in iCloud Drive as well in iCloud server .
https://support.apple.com/en-in/guide/mac-help/mchlp1774/10.14/mac/10.14
By unchecking the box of desktops and documents - the files and documents created are invisible temporarily both in iCloud Drive and www.icloud.com but they are not deleted from the server and still occupying the space , you can check the box and use get info and delete the desired documents any where from iCloud Drive or iCloud.com and restart the Mac and empty the trash .
You don't need to uncheck the keychain box from Mac system preferences , it will corrupt the iCloud Keychain settings .
Safari , Siri , find my Mac box must not be turned off .
Note : you can't remove desktops and documents box from Mac it is inbuilt .
