Google this week announced that parallel tracking becomes mandatory for all display and video campaigns starting July 31st, 2019. Parallel tracking for display and video campaigns will now be available starting May 1st, 2019.
Parallel tracking makes users browse the landing page faster as users are headed immediately to the landing page after clicking the ad while their browser processes click measurement requests in the background.
Google is advising advertisers to reach the click measurement provider as soon as possible, as any change of the URL will put ads on review. Google is recommending advertisers to pace the changes over multiple days.