OnePlus has since come forward to state that apparently this is “natural” and not a defect, but exactly what could be causing the issue? According to the folks at XDA, it seems that they have “confirmed” that the problem could have been caused by an upside down display, which was actually one of the initial theories that was put forth.
However we should point out that this is not a manufacturing mistake or error. It seems that the handset’s upside down display was done on purpose, although the exact reasons why is unclear. A teardown of both the OnePlus 3T and OnePlus 5 clearly shows that the display has been inverted, presumably for engineering reasons.
It is unclear why flipping the display is causing the jelly scrolling effect, but users have managed to replicate this effect on other smartphones simply by flipping their screens around. While this doesn’t exactly render the phone unusable, those who are particularly sensitive to things like frame rates might find the stutter annoying. Maybe you might not even notice it, so at the end of the day we guess it’s up to you whether or not you can live with it.