I’ll get this off the unanswered list.
Likely because it is fake.
The cartridge, which is usually black, is said to be grey. If we wanted to prove its validity further, we could look at the numbers on the cartridge or something, but this seems like enough to say that it’s totally fake, and it seems like you’ve gotten that figured anyways. As it is fake, it is more likely to have issues that an official copy wouldn’t.