Whenever I attempt to purchase a subscription, it runs an error ("Apple Error: Something went wrong while processing your payment, please try again!") after it tells me it was successful and takes money out of my account. How do I fix this?

Whenever I attempt to purchase a subscription for Discord Nitro Classic, it runs an error ("Apple Error: Something went wrong while processing your payment, please try again!") after it tells me it was successful and takes money out of my account. I've tried signing out, signing back in, deleting and reinstalling the app, restarting my phone, and turning on both Cellular data and WiFi (at the same time). I've requested a refund and been refunded 3 times for the issue, and I can purchase other items from other apps. Before being refunded, if I go to re-purchase the subscription, it states that I'm already subscribed to the service, although the benefits of the subscription do not appear on my account. Is there a way to fix this, or should I contact the app's support team?