Nothing stops the government from blocking your Pix transactions on a whim. They can just turn off your money whenever they want. They can confiscate your money any time if they want. They can do pretty much anything.
Conspiracy theory? It's cyberpunk stuff, the likes of which we see in fiction. Only it's not fiction. We're watching the whole thing unfold right before our very eyes.
I remember watching videos of people at events from many years ago. They warned us all about this stuff, explored all the possible consequences. It's pretty bleak. And now I'm living in this reality, the knowledge of the danger weighs down on me every day where I have to use the system. And people like you come here and calls us conspiracy theorists.