I have a website on Magento 2.2 and some customers wanted to use Visa Debit Card in the "Credit or Debit Card" payment option but they couldn't use a Visa debit card.
I'm wondering why they can not use the Visa Debit card in payment method?
To accept Visa cards, make sure that it is selected as an allowed credit card type. You can check the setting under Store>Settings>Configuration>Sales>Payment Methods. If Visa is not highlighted, then you need to select it and save the configuration and clear your cache.