File this under the quirky errors / wishful thinking category. The official android.com site has a list of devices including the Nexus 5X with detailed specs, but with one mistake: it lists it as having an AMOLED display instead of an IPS display.
The error was just brought to our attention by Redditor dbailyn, but it turns out it was spotted by another Redditor sekanato more than a year ago. As a matter of fact, a quick search shows a cache of the page from July 8, 2016 with the same AMOLED error.
It's not that the IPS display on the Nexus 5X is bad — I have one and always found it suitable for the price and usage — but it's still an error nonetheless. And one that's been going for more than a year, long after the Nexus 5X stopped being sold, and without being rectified.
At this point, just don't bother with it Google. I'm sure the page will be removed soon enough.