Almost everyone (very close to literally everyone) uses PIX and we have zero reported cases of mishap, errors or bad faith attacks...?
I quite frankly don't care that the system backed/created by the public services and imposed on banks is "closed"; to the point I'm generally curious as to what are the arguments for caring
Hope this does not sound dismissive - as a heavy user with no complaints for years, why should I care PIX is a black box?