It looks like the cat, well chip, is out of the bag.
A teardown of Xiaomi's beautiful Mi 8 Explorer Edition, which features a transparent back panel that lets you supposedly peek into the phone's innards to see stuff like a Qualcomm Snapdragon processor, has revealed that the chip you see isn't actually a sticker, but it's also not the actual processor either.
YouTube channel iFeng Tech got their hands on one of the Xiaomi Mi 8 Explorer Editions and proceeded to open up the phone. They discovered that while the board in question, seen under the transparent rear, is made from actual resistors and capacitors, the real motherboard is actually below it.
This tallies with what Xiaomi said in response to claims that it was a sticker: the components are real, they're not a sticker. What was left unsaid was that it wasn't the actual processor. The fake mainboard does have a purpose though, it seems to be used to connect the NFC module.
Check out the teardown video below.