For information about webhook logic in Binance Pay Docs

In Binance-Pay docs there is a point in Scenario Merchant Acquiring (C2B) – Payment by QR Code

so in the diagram there is circle at step number 19 and 20 which says when no webhook returns.
So my question is, is there a possibility that the webhook will not work or is there a possibility that the webhook will not receive.
Can anyone please explain me this point