You also don’t have to decide that “whiteness” stands for oppression in order to stand with justice. You just have to stand with justice.
Nobody should feel under attack because of the color of their skin. That is unjust. Yet that’s exactly what you’re doing when you say, “white people need to take responsibility for the toxicity of their whiteness.”
It’s not the skin color that causes toxicity. Saying so is standing with more injustice, just pointed in a different direction. A lesser injustice is still an injustice, even if there are greater injustices around.
Let’s listen to each other, take it seriously when people describe injustice, and work together to make our society equitable.