That's not true; PIX requires your bank to provide a way (called "MED"[1]) for you to request a reversal up to 80 (!) days after a transaction. It can only be used in case of fraud, and it may take up to 7 days for the bank to analyze the situation and deny/allow your request. If it's allowed, you'll get the money back in up to 4 days.
If the bank denies the request (i.e., if they conclude there was no fraud) you can always sue the transaction recipient; you'll have access to all necessary information since they must be registered with some financial institution to be able to receive a PIX transaction.
So it's not as easy as a credit card, but I think it's fair for a free payment service.
[1] in Portuguese: https://www.bcb.gov.br/meubc/faqs/p/o-que-e-e-como-funciona-...