EricIt's a flat textures pack, being used on a server that doesn't quite support the flat textures. This effect happens more with the Flat World Textures pack than with the Solid Textures pack, in my experience (but it can still happen with either). The Solid Textures pack also allows you to see through chicken wire/metal grate textures (2fort grate or old Snakewater), unlike the Flat World Textures pack, so I would recommend using Solid Textures over Flat World Textures.
thank you!