MacRumors published a story that Apple has released the third beta of tvOS 13.3.1 to registered developers.
Apple Seeds Third Beta of tvOS 13.3.1 Update to Developers
Apple today seeded the third beta of an upcoming tvOS 13.3.1 update to developers, one week after seeding the second beta and over a month after releasing the tvOS 13.3 update. Designed for the fourth and fifth-generation Apple TV models, the new tvOS 13.3.1 developer beta can be downloaded onto the Apple TV via a profile that's installed using Xcode.
Apple Seeds Third Beta of tvOS 13.3.1 Update to Developers