iPad Pro showing too much storage used in “files.” After using a hard drive

So... I have a 2018 base iPad Pro... I have iCloud photos turned off, and use a hard drive to store most of my old pictures. All of my keynote, Pages, and Numbers files are on iCloud, even my notability files. When I go to iPad storage, it says files takes 7 GB... But there’s nothing in my iPad’s files. On top of that, I just cleared my iPad’s photos and videos (4GB) to my hard drive.... And as I did that, files started to take 4 more GB, even after I disconnected my hard drive. I’m running out of storage and need to find a way to clear the files app’s storage.