The app creates sale prices and discounts by changing the values of the "Price" and "Compare-at price" fields.
It does this automatically for target products/variants in the same way as manual editing in the store admin panel, but much faster. In other words, the app changes the actual prices of products.
If a product only has a price set the app sets the current price as the compare-at price and applies the discounted value as the new price.
If a product already has both “price” and “compare-at price” you can choose one of two behaviors:
Deepen the discount — apply the discount to the current selling price
Replace the discount — calculate the new price from the current compare-at price (the compare-at price stays unchanged)
Price updates are applied in real time, so if your campaign affects many products or variants, activation may take some time to complete.