Apple wants to cut down on counterfeiting. The US wants to prevent supply chain issues and reduce reliance on foreign chip production. The wiki article on the CHIPS Act is a pretty good overview: https://en.m.wikipedia.org/wiki/CHIPS_and_Science_Act
Uhh. Who’s counterfeiting a cpu that only basically 2 factories in the world can make? Functional fakes are a thing for some really basic chips but an apple arm cpu seems like a little much.
Perhaps unauthorized is a better word than counterfeit. The manufacturing process for CPUs often yields less than ideal chips. Perhaps they don’t hit the clock speed they’re supposed to, or maybe they consume too much power. Those chips are supposed to be discarded, but they often find their way to the black market. Sometimes those chips aren’t even failures. If a fab overproduces, they’re not just going to give Apple the extra chips. These are the things Apple worries about, and they view it as far less likely to happen if those chips are made in the US.
I should also point out that the CPU isn’t the only chip that TSMC makes for Apple. Apple wants to make sure they’re getting a cut of every replacement part that gets sold. You can’t even swap screens on two brand new iPhones without Apple giving you a hard time.
