All payment card information is stored securely and encrypted at Tiptapp's payment partner, Stripe. Stripe is PCI certified, which means that they follow a standardised evaluation and reporting process for everyone who handles, collects, stores and transfers payment card information. Visa, Mastercard and American Express all support this approach.
Neither you nor I nor anyone other than Stripe can see the debit card details once they are registered. In addition, you only pay when you press "Confirm and pay" yourself after you have received help.
Stripe is a payment provider used by large companies around the world, so your card details are in safe hands.