Apple has released tvOS 13.4.8 beta 1 to developers just a few days post to the public release of tvOS 13.4.6 fixing a kernel vulnerability which helped the Unc0ver Jailbreak.
The build number for this beta version is 17M5535f and there are no new features spotted on this version as of yet but it brings in minor changes and improvements to tvOS. The letter ‘f’ at the end of the build number indicates that tvOS 13.4.8 will be released to the public after 5-6 betas.
If you have a developer profile set up on your Apple TV, go to Settings>System>Software Update and update your Apple TV. tvOS 13.4.8 beta 1 will support all devices supporting tvOS 13 which includes the Apple TV (4th Generation) and the Apple TV 4K (5th Generation).