Hi @jsb,
Thanks for sharing this question with our community.
While Klaviyo uses flow messages to ask customers to write a review, we don’t track if a profile has actually left a review, and customers cannot write reviews directly within the product review email they receive from you.
With that said, Klaviyo integrates with several different product review apps. Consider leveraging one (or more) of these apps to get more sophisticated in your product review strategy. As an example, Stamped.io will send Klaviyo an event when a positive (or negative) review is left. You could use one of those events to start a metric-triggered flow in Klaviyo. That flow can contain the thank you email with a discount code. I recommend reviewing their documentation for more information on pushing those review-based events to Klaviyo.
Thanks for being a community member.