If you attempted a transaction that failed with the error "Insufficient funds", it means your card is not adequately funded for the amount you're trying to pay. In other words, what you're trying to buy costs more than the money in your bank account.
Occasionally, your bank might decline a transaction because of “Insufficient Funds” and after you check your account, you discover that there are funds available for the purchase.
This can happen if there are other transactions in your account for which there is a temporary authorization, for example, a running subscription or a pending debit not yet deducted. An authorization can block the amount of the transaction in your account, thus reducing the available balance.
The authorization is time-bound and after it has expired, you'll be presented with your available balance.
What should I do?
To resolve this, you should fund your bank account to cover the difference between the amount to be paid or use another card that is adequately funded to make the transaction.
In cases where the "Insufficient funds" error is because of a lien on your bank account, you should reach out to your bank for the details of the lien that has been placed on your account and have it resolved.