But there's also other companies/services like Picpay and stuff right?
There are, and they are registered as payment processors or e-wallets. Facebook isn't.
Re:Brazil Suspends WhatsApp Payments
by Anarch157a on Thursday June 25, 2020 @08:35AM
(#23639931)
The Central Bank wants a system that's interoperable, so in certain ways, Pix promotes competition.
More likely Brazil's central bank doesn't want competition with its own payment system (Pix).