This is the explanation I found from Easy Street Bank:
“From September 2024, in Apple Pay you will no longer have the choice to select the payment network when you transact in-store. The Network Selection will be performed by the merchant instead of you, the cardholder, meaning when you pay using your card, it’s up to the merchant to choose whether the transaction is an EFTPOS or a Visa transaction.
You can still use Apple Pay the same way you always have by double clicking the side button and authenticating with Touch ID, Face ID or passcode.
Depending on the type of transaction account you hold and which the card is linked to, this means you may also incur a transaction fee depending on how the merchant chooses to route the transaction”.
From my understanding it’s legislation that the Reserve Bank Australia (RBA) has made to give control back to the merchants and out of the hands tech companies (Apple, Samsung, Google, etc).