Mostly that people now move between countries and tend to live and work in different countries than the ones the grew up in (obviously this is not the majority of the population, but is a higher proportion than even a few years ago), and the the US makes it very painful to be a citizen while living abroad. Plenty of people are fine with living in the U.S. and paying taxes in the U.S., or living in country X and paying taxes in country X. But living in country X and paying taxes in country X and the U.S. sounds very unattractive to a lot a people, especially if you have not lived in the U.S. for 20+ years...

If you are looking for a commentary one way or the other on recent political developments in the U.S., well, we have no clue yet, because all the data for H1Bs/GCs and citizenship renunciations both are probably from last year. Also, assuming someone moves to Canada tomorrow, it will take time for them acquire a Canadian citizenship and then from there to the point where they are ready to renounce their U.S. citizenship permanently, specially if that is right now their only citizenship.

H-1Bs do not have to pay US taxes for life no matter where in the world they go. It's just one more way that foreigners in the USA are privileged again and again over American citizens.