On a related note: I ordered BLF642 RF MOSFETs from Ali a while ago (because Digikey hiked up the price from $40 to $160 per piece in one day!).
Ali was still selling for the original price, and I thought those MOSFETs are too niche to be faked. Boy I was wrong!!
Ordered from 2 different suppliers, and both batches showed about 100 times less power output than expected.
I decapped the transistors to check the die, and those looked like LDMOS MOSFETs, but absolutely different from the original, and twice smaller in sizse. Also missing any marks. Compare the attached pictures, first is the original die, and the second is fake.
One seller agreed to refund, and another said that my pictures don't prove anything...