A chance to talk to FlatpanelsHD's reviewers.
Dolby Atmos on Apple TV 4K gen 1 and gen 2 is broken. Already since fw 15.x
Plops clicks stutters. Netflix most severe. Other apps as well. Without various brands of sounders and AV receivers.
Be warned!
BidiMc: We're not hearing it on our testing setup used to verify 4K, HDR, Dolby Atmos etc. (Apple TV 4K 2nd Gen + 2x HomePod with HDMI eARC + various TV models).

How is your setup connected? Are you using a receiver for example?

Since Netflix is the most severe could it be related to 24.000Hz output (as opposed to 23.976)? Are you getting it both with and without match frame rate activated?