My Apple TV started randomly going to black and then back to regular viewing. It's about a 1-3 second blackness. And it doesn't seem to happen with any regularity.
Intermittent issues are notoriously hard to diagnose. Check the cables, that all the plugs sit firmly in their sockets.
Now I restarted the Apple TV and the problem has gone away.
A good working device shouldn’t have to be restarted often, but a restart can cure some vague issues. Please report back if it happens again.
And if it comes back I'll change the HDMI cable
HDMI cables are all-or-nothing; they work or they don’t. If they’re broken, then the issues wouldn’t disappear because of a restart.
HDMI ports (on theTV or on a receiver or on Apple TV) are much more fragile.
… but if it persists is this an indication that the device is dying? The Apple TV is, approximately, 8-10 years old.
There are no moving parts. There are no gaps to collect dust. Electricity spikes and external force hits can damage it, though.
8–10 years ago is also a lot of innovation ago. Newer models have so much more to offer.
Identify your Apple TV model - Apple Support
Apple TV user guide (4th generation or later) - Apple Support