[jakopo87]

I quote from the link [1] you posted:

> To be clear, the respective blockchains will confirm blocks as normal and are not controlled by Binance. For the faster service, the exchange is accepting a reduced number of confirmations as sufficient to alter wallet balances within its own systems.

Binance and Coinbase on their own nodes can choose a lower number of blocks for confirmation but the network may reject it later, if that's the case they will have to put the transaction in another block to be mined.