My monthly subscription was INR 624.81, until December 2021. Why did that get doubled in January 2022?

Did you open your account in Oct 2021?

Hi there, @mohanmurthy-meds. I'll provide you with some information about your monthly charges in QuickBooks Online.

One possible reason is a discount that's no longer active. If this is the case, you'll need to pay the full amount of the subscription. You can check out this link to learn more about the prices: QuickBooks Online Plan and Pricing.

Moreover, you can use this page as a reference if you need a copy or to verify your payment history: View your QuickBooks Online payment history. 

Let me know if you have further concerns about your account in QBO. I’ll be here around to help. Have a great day!