Recycling old memory chips has been a trade for China's brands for a while. Not just GPU memory but also others like RAM, and NAND flash memory,... You may not know, but some China NVMe SSD also uses shitty or low-yield NAND or even recycled NAND from used SSDs. The same for some questionable Chinese RAM brands like Kingfast or Kingspec (copycat of Kingston name).
Dead VGA cards with untouched VRAM could still fetch a good price even if it not working or are completely dead (ten bucks for RX 470/570 model with 8GB last I check). To be honest, it was very eco to make use of everything even the old and busted memory of all kinds. Still, advertising it as a brand-new product is dishonest. My advice: don't take anything from China's market at the face value, check reviews from many other customers or broke-down, disassemble reviews like OP mentioned.
This is another reason why I believe gaming on a console is so much cheaper than PC gaming without having to worry about low fps and whatnot...now imagine having to invest in a GPU just to get better video memory or fps with lots of money for a used item that can die any time... and also the worst part about buying these products is that they are not covered by a warranty if you will be importing them from some other part of the world, in a nutshell, some bad business practice from our Chinese friends to be honest needs not to be supported.
No need to bring on the console vs PC war on this topic. Consoles have traits on their own, I agree with that. But for anyone who wants to tinker with their PC, wants to have more options, or might just simply want their gaming experience at both low heat and silent, PC is where you have every tool to tune for your needs.