In case of minor repairs, they are done directly in China
Supplies of the GeForce RTX 4090 to China have long been prohibited, and the RTX 4090D, it seems, will soon also stop being imported. Owners of such cards are reportedly faced with a situation where, if the card fails, they will not be able to get a replacement.
Nvidia operates in China, and therefore it and its partners need to provide warranty service. If the RTX 4090 suffers some minor damage, the card will be repaired directly in China and sent back to the owner. But if the adapter cannot be repaired, it all depends on the manufacturer.
If we are talking about a Taiwanese company, and these are Asus, MSI, Gigabyte and others, then the card is sent to Taiwan. And the problem is that the owner can no longer get the same RTX 4090 as a replacement due to sanctions. The money will be returned to him, but it is not a fact that he will be able to buy another RTX 4090 or even an RTX 4090D with it, if the latter actually stop shipping to China.