I know people on both sides of the political spectrum and there’s pain and confusion across society. Perhaps one side has more power in this moment and more harmful impact but making sweeping claims, "it’s all racism" is what makes a group feel unheard and angry.
It is because of racism. People were told about the invasion coming over the border, and that Trump would stop it, and they voted for Trump.
Having been skeptical of the racism explanation for quite some time, I've come around to it. Of course racism isn't the only thing that remains (there is also religious fundamentalism, spite, grift, etc), but it is a large chunk of what remains. I find the analogy of how communities destroyed their own public swimming pools as a response to desegregation an apt comparison.