Except these aren't liberals. These are progressives who got impatient with the slow pace of progress under the liberal agenda and to varying degrees have switched to the Critical Theorist agenda instead.

What you are seeing from "liberals" is profoundly illiberal messaging: the idea of common humanity is out, replaced by oppressor and oppressed classes vying for control (a la Marx).

White men are humans. Like other humans, they band together with their tribe to face a threat. "Liberals" (progressives) declared them to be the threat, so a lot of them banded together as the tribe that the illiberal left said they belonged to.

I think it's actually that simple.

The left decided to view people through the lens of identity groups, made the biggest groups enemies, and--what a shock!--the declared enemies identified less with the left.