The 5700X3D has the same core and thread count as the 5800X3D but with just slightly lower clock speeds, for less than half the price of the 5800X3D and wide availability:
From corsairs website:
The Ryzen 7 5700X3D and 5800X3D share very similar specs. However, the Ryzen 7 5800X3D offers a higher base and max boost clock of 3.4 GHz and 4.5 GHz respectively compared to the Ryzen 7 5700X3D’s 3 GHz and 4.1 GHz. Every other spec is identical.
These export restrictions on H20 chips went in place because the US does not want China to have access to the most advanced chips.
So, if Nvidia is not allowed to sell then the most advanced chips, why would they be allowed to teach them how to make those chips themselves?
An R&D center in China would have any designs made there be copied and stolen before the ink is dry on them.