Yeah, that's because of momentum scrolling that cause some devices (like Apple ones) to keep dispatching wheel events for a while. So imagine you flick the touchpad pretty hard and it goes to the next section but by the time it's finished animating, the touchpad is STILL dispatching a bunch of scroll events that are trying to continue the original motion - those scroll positions may be lagging behind, thus the browser is telling the window to scroll backwards which triggers that ScrollTrigger.