Free space in iCloud not less even after having deleted all files in iCloud Drive
Solution 1:
open system preferences and click on icloud. a new panel opens as shown below. click on the option button next to icloud.
After clicking the Option button a new panel opens. At the bottom of that panel is a checkbox to optimize mac storage. Make sure that box is unchecked. See 2nd figure below.
If the new icloud space doesn't look correct give it a few hours to update.