Yes. The mechanism is that American kids stopped learning useful things like STEM skills. I remember when I went to college in the early 00s, every single person in my physics class was either an immigrant, child of an immigrant, or Jewish. Now we have a shortage in engineering skills that has to be filled by H1Bs, and a population that all gets service jobs and consumes disproportionately because of an overvalued reserve currency. If that currency ever stops being overvalued, we're fucked.

Americans stopped learning or they were rejected?

Stopped learning. Physics classes at my college were about 12 students. CS and math would be about 20-30ish, History and English and Psychology classes were about 40-60, PoliSci could be upwards of 100. I don't think any science or math course there ever filled up. There was zero barrier to anyone wanting to take a physics course or be a physics major, other than the work being really hard.

Come on.