Apple’s Intelligent Tracking Prevention (ITP) feature was first released earlier this year at WWDC in an effort to increase consumer trust in Apple. ITP makes it harder for businesses to track peoples’ web use for advertising, and with the latest Safari 11 upgrade, Apple has made it even more difficult.

ITP 2.0 uses machine learning to detect whether cross-site tracking cookies from third-party networks can be used for retargeted ads. If so, those cookies only work for 24 hours and are wiped completely in 30 days. Cookies are basically small trackers that follow you around the web and store information about the content that you’re visiting and the actions you’re taking.

By limiting these cookies, it’s harder for online retailers to follow your browser trail. For example, if you were to look at a couch on an online furniture store, that furniture company might use cookies to advertise the item to you at a later time because you are more highly targeted and thus more likely to buy.

While Apple’s limitations are clearly in favor of customers who may find modern advertising tactics aggressive and prioritize data privacy, marketers depend on this information and have been using it for years. Especially as high-traffic shopping occurrences such as Black Friday, Cyber Monday, and the rest of the Winter Holiday season are upon us, ITP could affect the end of the year bottom line for many businesses.

In fact, six major advertising companies recently issued an open letter expressing their concern about the latest Safari 11 version. The letter states that with cookie-blocking technology as part of Safari 11, Apple is “sabotaging” the economic model of the internet.

Additionally, advertisers depend on cookies in order to personalize content. According to Adweek, the letter also stated, “Blocking cookies in this manner will drive a wedge between brands and their customers, and it will make advertising more generic and less timely and useful. Put simply, machine-driven cookie choices do not represent user choice; they represent browser-manufacturer choice.”

Perhaps this wouldn’t be so much of an issue if Apple devices weren’t as prominent as they are. Apple devices take up approximately 44 percent of all mobile devices in the US. And, unlike how Android suffers from fragmentation across operating systems, the majority of Apple users are quick to upgrade and are using Safari 11.

However, just because advertising tactics suffer on new devices doesn’t mean quality has to. While marketing teams struggle to find workarounds for ITP, software teams can continue to test on the newest mobile operating systems and devices with tools like CrossBrowserTesting.

By testing on Safari emulators and real devices, you can see exactly what your users are seeing when they visit your site on Safari 11. Hopefully, if retargeting doesn’t get them to come back, a great web experience will.