It's unclear what's new in this release; however, it likely contains bug fixes and improvements to tvOS 16.4 which introduced Dim Flashing Lights, an accessibility option to automatically dim the display of video when flashes of light or strobe effects are detected.
You can update to tvOS 16.4.1 by visiting Settings > System > Software Updates on your Apple TV, or you can download tvOS 16.4.1 from here: ● tvOS Download Links