Jump Sprinting on redstone wire produces greyscale particles

When jump sprinting on redstone, the particles appear like the greyscale texture, rather than red like the particles you get when breaking it.

As redstone is not solid, most of the time when you sprint on it particles of the block below are created, but if you jump while sprinting, redstone particles are created. To see them, make a line of redstone, look down, sprint on it and jump.