Issue with Payment Decline on Subscription Checkout

I’m experiencing an issue during checkout. I’m getting the error “Payment Decline: Please use another card.

Here are the details:

• The card is valid and works on other websites with the same authorized merchant, but using a different plugin.
• The order includes a subscription and is managed using the WooCommerce Subscriptions plugin for recurring payments.
• Despite disabling test mode and unchecking the option to save credit card information, the merchant is receiving email of transaction indicating that test mode is active.
• In the WooCommerce order section, the order status shows as “Pending Payment.”

Please advise on how to resolve this issue.