Doubt with formula in chapter 4x4 of the AoE X-Chapters

[Atomillo]

Hi!

I was reading the X chapters when I arrived at chapter 4x4 and more specifically at figure 4x41, which I attach.

Now, I understand that this compensation network creates a pole at the origin. In fact, this looks analogous to the Type I compensation network used in power supplies.

However, why is it that the frequency that crosses unity gain is determined by Rc and Rg in parallel? Following the before mentioned type I compensation network theory, the op amp virtual grounds makes it so that all current that flows through Rf passes directly to Cc, so that the crossover frequency is 1/2*pi*Rf*Cc.

How is the the Rf in parallel with Rg term determined? What is different from a type I compensation network?

Many thanks!