The update files are still sitting out there, probably. Go to disk cleanup, then advanced, and nuke ‘em.
I went to disk cleanup and there's nothing too big to remove
Select "Clean up system files"
What happens?
Yeah, I found the old windows files, I ended up reversing the update since a few apps weren't working. Still my storage is not the same before the update.
Before update I had 34 GB free
Now that I reverted 26GB free so some files still somewhere..