curl --request GET \
  --url https://api.salesbricks.com/api/v2/subscriptions/{subscription_id}/payment-methods/default \
  --header 'X-SALESBRICKS-KEY: <api-key>'

{
  "payment_method_id": "<string>",
  "is_default": true,
  "type": "card",
  "us_bank_account": {
    "bank_name": "<string>",
    "bank_type": "<string>",
    "routing_number": "<string>"
  },
  "card": {
    "brand": "<string>",
    "last4": "<string>"
  },
  "link": {
    "email": "<string>"
  }
}