Trying to confirm booking gives "The service associated to this request is no longer active" error ?

I reached out to a sitter to do drop-in visits for my cat and confirmed the details with them. However, when I click the "Accept request and pay" button and then try to click "Pay Now" with my payment information entered, a red pop-up message appears that says "The service associated to this request is no longer active" and the transaction can't go through.