Observer top texture has not been fully updated with the Texture Update

See attached screenshots. While the top textures do differ, it's clear to see that the current top texture still has more in common with the old "polished cobblestone" texture than the current one, and looks out of place when next to it. The arrow texture is the only element which has been substantially changed - the backing "polished cobblestone" is clearly identical to the old texture.

A fix for this can be found in the VanillaTweaks resource pack.