Apple will most probably add a toggle in the Location settings, which will give us the option to toggle on or off location for AirDrop. This feature is coming only to U1-chip-enabled devices, which are the 2019 iPhone Models. If you have an iPhone 11 or an iPhone 11 Pro or an iPhone 11 Pro Max, you can point your iPhone to another iPhone, and that iPhone will be first on your list so you can share your content quickly. The U1 chip is responsible for this, and unfortunately, it always uses Location services which may drain your battery, so Apple is planning to add a toggle for it in the future updates.
Apple may have also fixed an issue in this beta which would bypass the communication limits feature in Screen Time in iOS 13.3. A person discovered that if a contact is restricted, anyone can create a new contact of that person, and be able to communicate with them.
The Modem has also been updated in this update and switching from Wifi to Cellular may have been improved and the general performance of the devices have been improved.
iOS 13.3.1 would not have a long beta cycle, instead, it may end with 2-4 betas as there are no such new features in this beta, and it aims to fix bugs. The build number for this update is 17D5026c, also tells us that the beta cycle is not long, and that, we would see the final version soon. Most of us expected iOS 13.3.1 to be released to the general public but Apple pushed it as a beta to registered developers. All these changes mentioned above also apply to iPads with iPadOS 13.3.1 beta 1. Have a look at the release notes provided by Apple.