How did the conversation around undocumented immigrants become so vile?

Some of the stuff I'm hearing people on the right say, and even some moderates, around undocumented migrants is honestly concerning. It's like the conversation changed completely overnight and all I see for this group of people is dehumanization, anger, and straight up hatred. Hell, I've heard some people in support of death camps.

I'm looking for a kind of an unbiased academic answer, from level headed people, looking at the factors that led us here. No rude MAGA remarks, thank you.