tl;dr - Discount code creation & Discount code distribution do not happen simultaneously.
If you've enabled an Incentive in Junip & then visit your Shopify dashboard, you'll likely see a small number of unique discounts have been created all at once:
This is an intended behaviour & no, your customers are not receiving discounts by accident.
Shopify has something called "Rate Limits" on the ability for Apps like Junip to create discounts - this means, in the instance many customers submit a review at the same time, Junip might be waiting on Shopify to provide us with a code before we can display it to the customer.
To prevent your customer being disappointed & not receiving their discount, we create a small pool that are kept in holding - so Junip is always ready!