NPR was literally talking about this earlier in the morning, specifically within academia. I forget the speaker, but they cited that after Brexit, neighboring countries saw a rise in quality researchers who opted not to stay or study in the UK.
Honestly, even 2016 gives us some insight though and if I recall correctly, it never really caused significant brain drain. A little hard to measure people who never were here to begin with, but even my wife mentioned her reason for staying after the election and it’s because there’s still money to be made here.
I mean, it wasn’t too different 100 years ago. And the 1920s lead to a decade of economic stability, right? /s