All brands have settings in the cockpit that tell the POS system how many redemptions are allowed to be used in one visit. For Toast, when that rate is exceeded it will display the error message, "Error Validating Loyalty Account".
On the Toast POS back-end the error message will display as "You're unable to redeem multiple times in one visit, please try again later".
Redemption settings can vary from client to client, but is primarily set to one or two redemptions per visit to avoid fraud.
Here is an example that allows only 2 redemptions in four hours. Your CSM will be able to provide you additional guidance on how to manage these settings for your particular business needs.