Hello @Khurram-0890, sorry for the delay. Regarding the sudden increase in your Data Store consumption cost, kindly raise a support request with the Azure Billing support team at no extra cost to you. The billing engineers will be able to cross-reference your latest invoice with backend usage to determine the reason for the unexpected spike in cost in your invoice.
Hope this helps. Don't hesitate to ping if you have any follow-up questions.
Cheers.