Experiencing the same issue for over a year. On my 128GB iPhone XR, then on my 128GB iPhone 11, this "System files" category has steadily grown from 14GB to 35GB and now sits at 56GB, such that my total storage usage is 127.1GB out of 128GB. ■ When I upgraded my iPhone from XR to 11, I did it relatively cleanly and the System files began at under 6GB, but quickly and steadily grew back up. ■ Doing the "shutdown" suggested by Dumbbimbo used to work temporarily (dropping by as much as 6GB) but repeatedly doing it has less effect (now barely moves the needle). ■ I've now been forced to upgrade my iCloud+ account to the 2TB storage tier, 3x my monthly cost. ■ I can only believe there's some kind of memory leak happening with an app or system process, but have no way to find it. ■ I wonder, could it be associated with photo content volume (and edited files)? I'll start, so we can see if there's any correlation at all: 35.5GB in photos, 1.9GB in iMovie, and 56.0GB in System files.