The less economic and tech dependencies China has on the West, the more free they are to act on their own accord.
The US is concerned about Taiwan-- they wrote a blank cheque of support because it was a DeMoCrAcY back when China was a far weaker economy and military, and it will now be very difficult and expensive to stop reunification. Using TSMC as a shield is no doubt part of policy-- “invade and we blow the tech world back to 2010” is a viable threat until other countries get 7/5/3nm.
But their fear is more general; they are losing their economic and geopolitical dominance, and one of their big bulwarks-- advanced tech-- is giving way. They’re trying to hype up the fear and concern. Expect a lot more sabre rattling by the West.