I think there are multiple factors working here:
1. Hardliners angry about NVDA selling GPUs to China;
2. Board/Big investors want to get rid of him. They may think he is less important now that NVDA is clearly the top dog.
3. Political power trying to build up a case starting with him;
Anything else?
It's #3 and shortsellers. There's no one who can lead Nvidea, like he does with his technical depth, connections and trust within the company. Getting rid of him will be a loss for all investors and board.