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.
Biden wants to reduce US investment into China in aggregate and doesn't care where that happens.
I care where that happens 
This is the best summary I could come up with:
WASHINGTON/NEW YORK, Sept 27 (Reuters) - U.S. financial firms are pushing for greater clarity on proposed new rules curbing U.S. investments in some China technology sectors which they say are too vague and put the onus of compliance on investors.
Aiming to protect national security and prevent U.S. capital from aiding China's military, President Joe Biden issued an executive order last month restricting new U.S. investments in sensitive Chinese technologies.
Among their key concerns: how the rules would apply to U.S. persons; which specific Chinese entities would be subject to the restrictions; and better defining a proposed exemption for publicly traded securities.
"The scope is pretty broad," said Timothy Keeler, a partner at law firm Mayer Brown, noting it applies to Chinese entities operating beyond China.
Former Securities and Exchange Commission chair Jay Clayton, now an adviser with law firm Sullivan & Cromwell, voiced this idea when he told a House of Representatives committee on China this month that "Wall Street responds very quickly" to lists of barred entities.
Financial firms say they support the administration's national security goals but worry about increased liability and the economic costs of restricting capital flows.
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