Found this which clarifies the banking rumour
I heard I will have to give details of my bank account?
Nothing I have seen from the Spanish government suggests that will be necessary.
The business that you are paying must transmit the details of how you paid. For package holidaymakers, where the tour operator has paid the hotel direct, the answer will simply be “a voucher”. The same may apply for reservations made through intermediaries.
For most of the rest of us, it will be a credit or debit card, whose number and expiry date will be passed on. But if you happen to have paid the accommodation provider by bank transfer – which some people do – then your bank account location and number (but not the balance, nor any other information) will be passed on by the accommodation provider.