Fake thermal compound. It's apparently such an issue that Arctic has a scratch off authenticator site/code for consumers to confirm their product is real. I purchased the first tube on Amazon and didn't think much of it until Steve Burke from Gamers Nexus mentioned counterfeit thermal compound "was a thing" in a recent video. This gave me that bit of extra motivation to double check my paste, and sure enough it was fake. No scratch off/scratch off code on tube or box, no perforated shrink wrap on tube, low quality label printing, unverified codes.
I'm a bit puzzled because this is such an inexpensive product (under $10)……why the effort to make fake paste lol. I double checked where I got it on Amazon and sure enough it was sold by a third party seller with poor reviews. Just make sure you buy from Arctic (sold by Arctic) or a reputable third party seller, this almost caught me off guard.