I will answer. I might not be answering the question asked (it is too unclear for me to be sure), but my answer is to what I think is being addressed in the linked book. (And if this question gets muddied in confusion, I may pose a related question soon.)
How is the teaching of mathematics sullied by racism or white supremacism?
The naming of theorems and mathematical objects is eurocentric: * We speak (in the U.S. and I'm guessing many other countries) of Pascal's Triangle, yet it was invented many times (long before Pascal lived) in India, China, Persia,and others. (See wikipedia.) * The Pythagorean Theorem was also invented long before Pythagoras, in other cultures. (I know the argument that Pythagoras was the first to prove it. I doubt that that's accurate. We don't know all of what happened in those other cultures. Archeology is not great at getting all of the written records.)
Math classes have been used as a filter for decades or centuries, to weed people out of certain professions. Think about doctors, for example. Are they required to do more math than they need? And lawyers, perhaps? So there used to be this mindset that it made sense for lots of students to fail. Who failed? Why? Look at the funding of our K12 systems in the U.S. and you see that economics (and race) are deeply involved. Why is race involved? The best book I know of on this is The Color of Law, by Richard Rothstein. Here's an article about his work. Basically, our education system is funded by property tax, and our country was segregated by laws put in place by the government. Our history is a mess.
If we are trying to be anti-racist in our teaching, what can we do? There's a lot, and that book is trying to lay it out. Mathematical facts may be objective in a way we do not find problematic, but the choices of topics to cover in each course is not as objective as that. And stopping students from taking college level courses because of holes in their education has racist effect. If we can do things differently, we must. One solution that's happening in California is for students who are not interested in STEM to take statistics, and if their background is weak, to have co-requisite support. For students interested in STEM, it's a little harder, but I tell my students that it's my job to help them get from where they are to where they want to be. (And their job is to do the work it takes, while I guide them.) I explain misconceptions about fractions to my calculus students.
I will stop here for now. Yes, there are books about this. It will take books and good will, and effort from us all, to change the racist world we are living in.