It's not actually a weatherstrip - it's just a cosmetic gap concealer. If you look at the other side you'll see that it doesn't actually seal against anything or redirect the water anywhere else.
Some line manager apparently noticed that the updated power strut *almost* touches the rubber strip and concluded that it would be better to crudely hack off a foot of it, leaving an unsightly gap, than to take the risk of the strut possibly almost gently touching the edge of the rubber. They also install the rear windows a little off-center to be extra sure.