They implemented by the end of 2019 the SRM (MED):

Special Return Mechanism

The Special Return Mechanism (SRM) comes into play in cases of well-founded suspicion of fraud, whether actively identified by the institutions involved or when a user initiates a Pix transaction but soon realizes they have fallen victim to a scam. In such situations, it is necessary to file a police report and immediately notify the institution through official channels, such as customer service or the ombudsman. Within the Pix environment in banking apps, there is a direct link to the designated channel for filing complaints.

The victim's bank, in turn, will utilize the Pix infrastructure to notify the receiving institution about the transfer, so that the funds can be blocked. After the blockage, both the payer's institution and the potential scammer/fraudster's institution have up to seven days to conduct a more thorough analysis of the case to confirm that it is indeed a fraud. If the fraud is proven, the destination institution of the transaction returns the funds to the payer's institution, which must then credit the customer's account accordingly.

You don't actually know there is a file from the buyer, and you get your funds returned by surprise, so at the sellers point of view, there's no wait time, since he doesn't know there's a complaint.

Pix favors buyers, ergo, buyer is innocent until seller proves otherwise!