iOS 11.4.1 should improve the reliability of AirPods, along with syncing Mail, Contacts, and Noes with Exchange accounts. watchOS 4.3.2 and tvOS 11.4.1 should just have general fixes and improvements.
The toggle is off by default, which means that once your iOS device has been locked for more than an hour, the operating system will no longer allow USB access to connect to the device.
If you think back to the tragic San Bernardino shooting incident of 2015, you might recall that Apple refused to build a software backdoor for the Federal Bureau of Investigation to access one of the killers' phones, fearing that doing so would set a unsafe legal precedent.
But it was Grayshift's decision to mass produce a small box called Graykey and stick it on the market for $15,000 that forced Apple to shut down the entry point. USB Protected mode is the biggest new feature which is aimed at making it harder for hackers to access your iPhone's data via USB. Importantly, this only helps if the iPhone has still not entered USB Restricted Mode. It may be that cops are issued with cheap accessories to make this possible. The battery indicator reportedly dropped to 40% over that time. But for now at least, iPhones, with this update, are locked down.
As the version number indicate, there are no new features in these builds. And very little information about how it works. Apple hasn't even listed any of the updates on its security update page.
These fixes address various bugs, some of which can be exploited by webpages to execute malicious code on vulnerable devices.