iOS and iPadOS 13.3.1 can be downloaded from the Apple Developer center or over the air once the proper developer profile has been installed.
iOS 13.3.1 includes a “Networking & Wireless” toggle that turns off the U1 Ultra Wideband chip in the latest iPhones. The feature, located in the Privacy > Location Services section of the Settings app, turns off location for Bluetooth, Wi-Fi, and Ultra Wideband.
Apple added this location toggle after it was discovered that the iPhone 11, 11 Pro, and 11 Pro Max continue to track user location even when location services options are disabled. This is because there are international regulatory requirements that mandate the U1 chip be disabled in certain locations.
The new toggle makes sure location tracking is off for the U1 chip at all times. Apple has also added a new “Play Again” button when replaying content that you’ve already watched in the TV app.
Along with these features, the iOS 13.3.1 update also likely includes bug fixes for issues unable to be addressed in the iOS 13.3 update. Specifically, it could address some issues with Communication Limits, fixing a workaround with the Contacts app that allowed children text someone who contacted them from an unknown number.