It has been a big fascist thing in Europe (Brexit was all about it, IMO) and IIRC, Hitler played this card.

They all do at some point. Musical scapegoats.

Here, it's done because it enrages and engages the hate cult.

From around 1920-1960, very little immigration was allowed, including of Jewish refugees from Europe.

With the rise of AI, far fewer workers will be needed. The ultra wealthy seem willing to have some of the workforce die off via less medical care, reduction in vaccination, and so forth. And an influx of workers will not be needed, so it is best to keep them out. Fewer people means fewer mouths to feed, fewer people to provide benefits to, and fewer people to share wealth with.
They would seemingly like to take us back to a feudal society.