MacRumors published a story that Apple has released the second beta of tvOS 15.4 to registered developers.
Apple Seeds Second Beta of tvOS 15.4 to Developers
Apple today seeded the second beta of an upcoming tvOS 15.4 update to developers for testing purposes, with the software coming two weeks after Apple seeded the first tvOS 15.4 beta.
Apple Seeds Second Beta of tvOS 15.4 to Developers
Developers can download the new tvOS 15.4 beta by downloading a profile onto the Apple TV using Xcode.