While the Files app for iOS and iPadOS gives you access to browse iCloud Drive, some parts of local storage, and third-party cloud storage, it omits a critical piece of information that’s been a useful part of file navigation since the start of computing: the storage occupied by a folder (or directory) and everything contained nested within it. This makes it effectively impossible to figure out what’s occupying your iCloud storage if you need to remove it to make room for other files.
Launch the Files app and you can see for yourself. Tap iCloud Drive and any file at the top level is listed with a name, date, and size. Folders, however, just tell you how many items they contain—and that’s only at the top level, not including any nested items layers of folders deep. iCloud.com is even worse. You have to click an “i” info button on a file to see its size.