iPhone is out of storage with no apps or media

Hi Apple community members,

I have a pack of iPhone 7 and iPhone 7 Plus models purchased from T-Mobile and it keeps running out of storage even with no apps installed, I tried a factory reset by erasing all content and settings by going to settings general reset erase all content and settings, after I erased the phone, it says no service but once I activate it, there is no service until about one hour and 48 minutes of activation, as I watched the available capacity go down and down every several minutes, once it reaches about 56 MB available, the service comes back on and you cannot install any apps. For reference, all of the iPhones purchased from T-Mobile that I own are all 32 GB model, but the iPhone 7 and other devices purchased from Apple does not have this problem