A day after a short-cycle in the iOS beta testing period, Apple has made available tvOS 11.2.5 beta 5 to developers for testing.
As with the rest of the tvOS 11.2.5 beta 5 releases, Apple has no specific foci of testing, nor do the notes accompanying the download mention anything of any substance. As such, it is not clear what the new release contains, other than assorted bug fixes, and probably rectifications for "Meltdown" and "Spectre" CPU attack vectors.
The new versions are all available to download through Apple's developer portal. Public beta builds should be forthcoming as well.