How do I debug Razorpay Standard Checkout for Subscription in production?

Question

I have integrated Razorpay Standard Checkout for Subscription in my application. The integration works perfectly in test environment but in production it fails mysteriously. The payment options are shown but if I try to pay by upi id or mobile number or even try to display qr code for scanning, it fails with a very generic error

{
    "error": {
        "code": "SERVER_ERROR",
        "description": "We are facing some trouble completing your request at the moment. Please try again shortly.",
        "source": "NA",
        "step": "NA",
        "reason": "NA",
        "metadata": {}
    }
}

It works perfectly in test environment so I expected it to work in production as well. Support ticket is raised on 13th Feb and still not a single response.

From network tab I can see the razorpay api responded with a 500 but no further details.

Am at wits end and contemplating a switch to some other payment gateway because of this blocker issue and absolute lack of support from Razorpay.