Cash App Payment Failed Touch Id is the feature that allows you to authenticate a transaction. Therefore, if there is an issue in the Touch Id, then you can get it fixed by cleaning the sensor of your phone. If that doesn’t help you with the issue, then get to customer care for more information and support.
https://www.apple-supportphonenumber.com/blog/why-is-my-cash-app-payment-failing
https://www.apple-supportphonenumber.com/blog/why-is-my-cash-app-payment-failing