Generally, the mandate for IPO applications is revoked post allotment. On revocation, funds will be unblocked in your bank account. The mandate request has a specific end date as shown below.
Important Note : Some banks may wait till the end date of Mandate to complete revocation. You can check the mandate end date on your UPI app. You can raise a request with your particular bank to release funds anytime post allotment date in case you have not received an allotment of shares.