Xayah's passive has a fixed travel distance
This is apparent while playing, but anyone who has built Rapid Firecannon on her can see that this reduces the effectiveness of the item, despite it being her recommended zeal item.
While the energized auto attack will have more range as usual, this does not apply to her passive. The passive feather won't go as far behind the target as ones thrown from her regular range would. This gives a fleeing enemy a bigger opportunity to escape the root.