They have a photograph of the chip and scores of (unfortunately anonymous) sources.
It sounds like some researcher found weird traffic, eventually found there is a chip on some of these servers that wasn't in the original gerber files, and this chip is doing something, and beyond that a lot of people are speculating about who and what.
Apple and Amazon deny that the story is correct. That doesn't mean that there isn't a chip there and they now know what it is doing but are prohibited from saying much beyond the story as a published whole is not true.
It sounds like some researcher found weird traffic, eventually found there is a chip on some of these servers that wasn't in the original gerber files, and this chip is doing something, and beyond that a lot of people are speculating about who and what.
Apple and Amazon deny that the story is correct. That doesn't mean that there isn't a chip there and they now know what it is doing but are prohibited from saying much beyond the story as a published whole is not true.