Full Answer

Link decoration is the technical term for what happens between an ad click and your landing page URL, and Safari's treatment of it fundamentally reshapes how WooCommerce stores must think about attribution.

When a user clicks a Facebook ad, Facebook appends fbclid to your landing page URL. Google Ads adds gclid. TikTok adds ttclid. These parameters decorate the link with an identifier that ties the click to the ad platform's campaign data. On your WooCommerce site, JavaScript reads this parameter and stores it in a first-party cookie so that when the user converts — potentially days later — the conversion can be attributed to the original click.

Safari's Intelligent Tracking Prevention disrupts this flow at a precise point. When ITP detects that a user arrived via a link decorated by a classified tracking domain, it downgrades the lifespan of any JavaScript-set cookie from 7 days to 24 hours. The parameter itself survives the initial page load, but the cookie storing it does not survive beyond a single day.

The 24-hour window is the critical constraint. For WooCommerce stores selling products with consideration periods longer than a day — furniture, electronics, subscription services, anything requiring research — a significant percentage of conversions happen outside that window. Server-side tracking changes the equation by capturing attribution data during the first visit and storing it in your own infrastructure, making browser cookie policies irrelevant.