Here in the USA, Trumpists are very hostile towards immigrants coming from the Mexican border to the point where they infamously proposed to build a wall. The Biden administration is better in-name only, and has kept the concentration camps at the border.
Why is there so much hatred toward these immigrants? What is the material cause of this?
The material basis is that the bourgeoisie benefits from enforcing strong borders. If there were no borders, then workers could move freely, and that would give them more power.
Nobody really wants to shut down immigration entirely, but they want to maintain strict control of it in order to maintain discipline in the labor force.
Tell that to europe