Last week, I made the move from a Lumia 950XL to an iPhone XR (absolutely miss the camera button.)
Today, I received an email from Apple stating that I have used over 50% of my iCloud storage. I was bewildered, since I do not use iCloud for anything other than backups, and when I checked in settings, I was using 142.9 MB of 5 GB, or 2.8%. Maybe this is how they increase service revenue.