MacRumors published a story that Apple has released tvOS 15.4.
Apple Releases tvOS 15.4 With Support for Captive WiFi Networks
Apple today released tvOS 15.4, the fourth major update to the tvOS operating system that first launched in September 2021. tvOS 15.4 comes less than two months after the launch of tvOS 15.3.
Apple Releases tvOS 15.4 With Support for Captive WiFi Networks
tvOS 15.4 can be downloaded over the air on the Apple TV through the Settings app by going to System Software Update.