A discount that appears just as a shopper moves to close a page is not a coincidence. It is triggered by observable behaviour, and the timing is the point of it.
Departure is detectable before it happens
Browsers report cursor movement, scrolling and page focus, and a rapid movement towards the top of the window is a reliable indicator of intent to leave.
Inactivity, repeated switching between tabs and rapid scrolling to the bottom of a page serve as additional signals.
Software watches for these patterns and fires an offer in the moment between the decision to leave and the departure itself.
The offer is sized to the basket
Because the basket contents and value are known, the discount can be calculated against the margin available on those specific items.
A high-margin basket supports a larger offer than a thin one, so two shoppers leaving at the same moment may see quite different amounts.
The aim is to offer the smallest incentive that converts the sale, which is why offers are frequently modest and occasionally do not appear at all.
Email capture is often the real objective
Many exit offers require an address before revealing the code, which converts an anonymous visitor into a contactable one.
That address is worth more than the single sale, because it permits an indefinite sequence of later marketing at almost no cost.
Where the discount is small and the requirement is an address, the exchange is closer to a purchase of contact details than to a price reduction.
Abandonment sequences continue afterwards
If the shopper is already identified, leaving a basket usually triggers a series of reminders over the following days.
Those messages often escalate, starting with a reminder, moving to a scarcity claim about remaining stock, and ending with a discount.
Waiting through the sequence is a well-known way to obtain the largest offer, though stock and price can change while waiting.
The tactic trains the behaviour it responds to
Shoppers who learn that leaving produces a discount begin to abandon baskets deliberately, which erodes the value of the technique.
Retailers counter by varying the offer, withholding it from repeat abandoners, and limiting how often a single account can receive one.
The outcome is an unstable arrangement in which both sides adjust continuously, and any consistent pattern a shopper notices tends to be short-lived.