Excessive input.
Only input enough to prevent tipping. Do planes tip parked sitting on the ramp? No, so no roll input is needed at the start of the takeoff roll. As the plane accelerates put in just enough roll input to keep the wings level. Typically that means nothing until above 80 to 100 kts and just minor inputs after that. Think "less is more".
Boeing states too much input does reduce tail strike clearance.