Your profile shows that an iPhone is used see the article https://support.apple.com/en-in/guide/mac-help/mchle5a61431/10.15/mac/10.15
The reason why documents are showing empty still occupying the cloud storage space .
Important: After upgrading to iCloud Drive, your documents stored in iCloud Drive are only available on your computers and iOS and iPadOS devices that meet minimum system requirements and have iCloud Drive turned on. Your documents in iCloud Drive are also available on iCloud.com.
If you have devices with iCloud Drive turned off, documents and data on those devices aren’t kept up to date with documents and data on your devices with iCloud Drive turned on.
Also read the last paragraph of the article .
You can manage the iCloud storage : https://support.apple.com/en-in/guide/mac-help/mh36833/10.15/mac/10.15
https://support.apple.com/en-in/HT204247