I'm estimating the trends correctly:

1) Subtantially less (like single digit %) PRC tier1 talent are leaving now, and more skilled talent are flowing back from west to PRC due to better opportunities. Record number in last few years. What you're seeing is some old wealth, accumulated in PRC at time when you didn't need high skill talent, capital flighting. And a bunch of low skilled migrants trying to enter from south America to flip burgers. This isn't the 2000s where best of best PRC goes abroad, some do, but largely it's the extra mediocre/dumb who can't hack Chinese gaokao. This isn't diasphora from 90s where every Chinese group has friends who were like top10 from their province. The common story now is my kid too dumb/fragile to survive PRC tertiary, lets send them abroad. Which relates back to old wealth fleeing, a lot of rich peasants who guanxied their way into wealth and know their kids aren't smart enough to do well in PRC but maybe can coast in west where talent pool is shallow. Like this

2) Except they're climbing/leading science/innovation indexes in west controlled for quality. As if university in the west don't have retarded waste of time rereqs. No one is learning XJP app for 3 hours a day. They're studying their courses and farming primogems.

3) Yeah they're going to spend years bumming a round while job creation meet talent creation, which is expected artefact of PRC overcapacity. That'll sort itself out in a a few years. Supply/demand etc. The important point being, right now there are host of significant, strategic industries where there's lots of demand and having excess talent is net good, i.e. PRC is basically the only country on trend to not have talent shortage in semiconductors in 5 years. And guess what happens when there's extra demand, companies take and retrain less qualified applicants. It's better to have a pool of STEM taxi drivers who can skill work because you know they were filtered by tertiary system than the west who has excess demand for skill work, and taxi drivers who can't.

4) Now break down the numbers. US has access to global talent, but what US actually has access is 400M english speakers, 600m with some english proficency, from a few countries with skill development. And guess who they have overwhelmingly chose in the last 10-15 years. PRC talent, that they are now making harder to brain drain due to domestic policies. Meanwhile, PRC has 900m mandarin speakers, but realistically like US, the subsect of viable tertiary talent is much lower. But PRC talent bias skill/technical work, vs gender studies and has much bigger pool for high skill work. Meanwhile, they've been retaining significantly more talent due to more opportunities, and frankly produce so much that US/west can't even brain drain enough to make a dent, assuming US/PRC domestic politics allows prior levesl of brain drain. US has access to "more" talent, but realistically can only takein/incorporate so much. Meanwhile PRC has access to MORE talent, more than US can ever take, including top end.

Very few are skilled youths driving did/meituan. Some do, but youth umemployment stats concenrates low skill. Credentialled youth and taking their time job seeking, looking into teaching/government, and eventually will settled into bluecollar work that pays better than delivery work if they can stomach the shame. Broke, medicore skilled youth, the C students are desperate enough to do low end work. If you're an A level talent, you're already working sometime nice. No so different from advanced economies as they deal with academic inflation.

Conspiracy/FLG/and that one professor guess 1.2B. Which doesn't even matter since output of PRC exports and value chain can be measured by proxy. That 1.2B is consuming resources for previous 1.4B, and living 10% better. It's fine. And as if PRC having 200M less mouth to feed and fuel is actually a problem. Meanwhile commodity imports and energy increase trend is clear and can't be systematically fudged over timescale. Dang's not going to be happy if I interrogate every luny claim on PRC. Suffice to say, PRC skilled demographic boom, and ability to to coordinate them is so large, that they have large advantage even if you think they're fudged by double digit percentages.