The company recently released a beta version of the tvOS 13.4 software update for Apple TV set-top boxes. It contained mentions of an unannounced Apple TV, 9to5Mac discovered. The references indicated this upcoming Apple TV uses the same architecture found in the A12 and A13 Bionic chips, indicating it runs on one of those chips. The current Apple TV 4K uses the A10X Fusion chip.
Add it up, and the company is likely preparing to debut a new Apple TV with much more powerful hardware, although, to be honest, the existing Apple TV 4K is already one of the best set-top boxes you can buy. Apple nevertheless probably wants to make sure its next streaming media player can properly handle everything the new Apple Arcade and Apple TV+ services can throw at it.
There's no word on when this device will appear. Apple sometimes holds an event in the spring, so perhaps we could see it appear then. It's still early days, however, and we haven't seen much other evidence to suggest a new Apple TV is coming.