I'd say there is a large difference between the portions of the production lines sources from China and those sources from the US. The largest of which is that,

I'd say there is a large difference between the portions of the production lines sources from China and those sources from the US. The largest of which is that, for those portions sourced in the US there is no alternative supplier, which is likely how the US is able to enforce such export controls. I think a better way to look at it is: the US is allowing TSMC to use export controlled equipment outside the US, in exchange for TSMC abiding by their restrictions.