I'm sorry, while I have no insider knowledge, this rumour sounds a bit confected. Nvidia released a statement saying it wasn't concerned about the 4090 restrictions if they came in so...
Because it is affecting the raw AD102 silicon.
When AD102 at its original state, with its full potential, can be used in manufacturing products for AI/Enterprise/Military application, thus being restricted.
For the 4090 card, these capabilities of the AD102 inside had been physically fused/ limited by microcode, so it is a "Commercial Product"
So the manufacturers having their sites located in China cannot have the AD102 chips being exported and shipped to their doors anymore.
So they will have to relocate.
But before relocation, they want to utilize these final moments to put out as many 4090s as possible with existing facilities.