Why does it take 72 hours to credit my bank account for my gold sell transaction?

Paytm Gold
Why does it take 72 hours to credit my bank account for my gold sell transaction?

To ensure that your gold is secure, we closely monitor your sell transaction for any risk. Thus, in certain cases, we introduce a safety period and credit the amount to your bank account after 72 hours of your sell transaction. Nonetheless, the gold balance from your Paytm account will be deducted instantaneously so that you do not miss out on the current gold price.