There was a law that prohibited Taiwanese companies from building leading edge process fabs in China, I can't recall the specifics but it had to be lagging two or three process nodes to be green lit by their government. I don't know if it is still in effect and can't recall if it was specifically targeted towards China or applied towards any fabs built outside of Taiwan. Then again, I suppose even if it wasn't directed towards a fab built in the US, if this fab won't be putting out anything until end of 2023, it might already be considered two nodes behind their leading edge and perhaps the Chinese could coerce them to do that. I guess the question comes down to timeframe if that law is indeed still in effect, they could build a 5nm fab in China years in the future as long as it doesn't conflict with their laws!