There ARE so called "fake" CPU in the markets

the scammer will usually delid the CPUs, swap the IHS of the old one with a new one, for example a CPU IHS there stated it's a 5950X, but it might be just a 1200 underneath, you wouldn't know until you've booted it up

But fake delided CPU for AMD is pretty rare compared to Intel as AMD soldered their IHS, making it extremely difficult to delid
Another method the scammers used for AMD CPU is sanding off the labels on the IHS, and print a fake label as higher spec CPU