Customer card declined when processing payment
There are a number of reasons why a customer's card could be declined. You can read about the main types of declines and ways to address them in the Understanding Declines and Failed Payments guide in Stripe Docs.
Certain declines might be preventative measures working in your favor to minimize the possibility of a fraudulent payment, that otherwise could result in a dispute.
Understanding Declines and Failed Payments (Stripe Docs)