iCloud storage -grey portion

What is the grey section? I am using an older iPad mini and it has the free 5GB plan. The only items syncing with the cloud are photos, files and notes. While the status shows I am using 3.5 of the 5GB, my photos and notes only total 2.2GB. The balance of the used space is grey with no title.

While I am not sure of the size of the "files" (and if that is actually the grey space), someone needs to tell me the untitled grey space is actually the "files". And how do I know that is "files"? My iPhone shows "files" as something occupying space locally on my phone.

I reset the iPad back to factory settings and signed in. I added no app or profiles.

Help.