Apple USB Restricted Mode or USB Accessories Mode/Lock was introduced with iOS 11.4.1. There was a rumor that the lightning port would be locked down, preventing brute force unlocks (Grayshift and CAS, Premium), and it came about when iOS 11.4.1 was released into beta. When the user updates to iOS 11.4.1, the USB Restricted Mode is automatically enabled, which means USB Accessories is turned off. To view this setting on your device, go to Settings>Face ID & Passcode > USB Accessories—it’s actually enabled when the toggle is turned off (to the left, not green). Magnet Forensics and Elcomsoft wrote blogs on cables that may prevent this mode from becoming enabled. Essentially, when you get the device, you immediately plug it in. At the time of writing these edits, iOS 13 seemed to remember the trust on PCs longer than expected.