It looks like your client-side code is using the example from Stripe's React code snippet instead of the React Native snippet, right? It looks like their React Native library is expecting snake case instead of camel case: notice the error message says "only accepts the USBankAccount payment method type" instead of "us_bank_account" like they document in the API reference.

https://docs.stripe.com/payments/ach-direct-debit/set-up-payment?platform=react-native