Some OnePlus 5 users have been complaining about this jelly-like effect when scrolling through an app on the phone. OnePlus just addressed, or should we say dismissed, this issue saying that it’s a normal thing for the device. In a statement, they say “the OnePlus 5 uses the same level of high-quality components as all OnePlus devices, including the AMOLED display. We've received feedback from a small number of users saying that at times they notice a subtle visual effect when scrolling. This is natural and there's no variance in screens between devices.”
Because of this announcement, unfortunately, it would seem filling a warranty replacement won’t get you anything. But if this bothers you and you’re still well within the 15-day return policy, then that seems to be your only recourse at the moment.
Source: The Verge