iCloud shows storage being used but files are not visible

Solution 1:

Your PDFs and books stored in the Books app are taking up your 2GB of storage. You can disable these documents uploading to iCloud in Settings > Books. Disable the switch labeled "iCloud Drive."

When you download a document in Safari, it goes to the location specified in Safari settings. You can open Settings > Safari > Downloads and see what it says. On my phone, it says "On My iPhone / Downloads." To view these documents, open "Files" and click Browse tab to navigate to the location mentioned above. For me, that means clicking "On My iPhone" under "Locations" in the Browse tab, then clicking the Downloads folder.