I would expect tons of H1Bs from former soviet bloc countries that have incredible math and science education. The fact that the H1B program isn’t clogged with Russians and Ukrainians is evidence something is amiss.

You'll notice it follows a population distribution of the world, with higher weighting from less developed countries. Soviet bloc people are not a high %age of world population and also tend to be captured more by europe since it's closer. People from developed countries tend to have less incentive to move on top of that. Indians have a further advantage of already knowing english on top of that and you get our current distribution of mostly people from india, china, canada (proximity, easy TN visa and english), europe with significant slavic representation and then everywhere else in the tech industry.