iPad 2017 (currently running iPadOS 13)
I primarily use my iPad for reading and have about 200 documents in Books (PDFs and ePubs; none downloaded through Apple.)
When I go to the iCloud settings in my iPad, I see 2.1 of 5 GB being taken up by documents (and those alone). Only Safari, Books and Acrobat Reader are enabled under 'Apps using iCloud', along with iCloud Drive.
On icloud.com, it's similar: 2.06 GB used up by documents, but when I go to iCloud Drive it's empty except for couple of documents.
Every time I download a new document or rename it, I see a little cloud symbol momentarily pop-up next to the title. I assumed that the documents were being uploaded to iCloud drive, but I'm not able to find them.
Could someone please help me figure out why cloud storage is being used while the documents are missing?