Not clarifying the curbs is the entire point. Biden wants to reduce US investment into China in aggregate and doesn’t care where that happens. The “totally tight and totally limited” curbs are just a cover that Biden is using to justify his policy.
The US definitely cares where that happens. They could give a rats ass if every stupid trinket, knick-knack, or unsophisticated gadget was manufactured in China.
What they care very deeply about limiting is high-tech developments, semiconductor fabrication, and heavy industry.
These pose a serious threat to the US’s ability to subjugate the rest of the world into allowing indefinite extraction of natural resources. Why do business with the West when China will provide technology that is of equal or superior quality with fewer strings attached? China has an extremely low bar to clear in terms of equality of exchange, and only needs to keep developing itself to put an end to US hegemony.
At which point, the rest of the world can sanction and exclude the West because the West largely extracts while producing very little in terms of material goods.