'iCloud Drive' taking up storage on iPhone

I have 'iCloud Drive' taking up 29/128 GB's of storage on my iPhone XR.

I did not try to access any files that are stored on iCloud through my iPhone. Also, I never even had 29gb worth of files on my phone (excluding apps, photo's, video's, etc., which are listed separate from this 'iCloud Drive'). So it cannot be 'files there are stored in iCloud but are accessible on the iPhone and therefore take up local storage', like Apple Support always seems to think.

I have contacted Apple Support multiple times about this, and no one seems to understand it. Everyone just links this page: Manage your iCloud storage – Apple Support (UK)

which of course doesn't explain anything, if you understand the question.

So, does anyone from the community maybe know this problem? And maybe even a solution?

Thanks in advance!