This is a known issue with Netflix on the ATV4K. Not everyone experiences it, but nobody has figured out why as of yet.I am glad you mentioned Netflix, I seem to get popping/cracking sound in my speakers only with Netflix shows that are Dolby Atmos, most of the time somewhat annoying, but when I was watching the series F1: Drive To Survive, it was really bad, maybe because more LFE, roar of engines, etc. Could be my Dynamic Range setting on my Pre/Pro didn't like it?
Netflix is almost certainly aware of it, but there's no telling when it will be fixed.