The Bamboo Trapdoor's texture is incorrectly oriented, assuming the 4 lightened pixels are meant to represent a handle. In the texture file, the handle on the Bamboo Trapdoor is at the top, whereas in other Trapdoors with handles, the Birch, Mangrove, Acacia, and Jungle Trapdoors, the handles are at the bottom. In game, this manifests as the trapdoor's handle appearing on the hinged side of the block on the top and bottom, and visible on the sides of the block, whereas the others have the handle opposite the hinge, and not visible on the sides.
I would like to note that this is NOT a UV-mapping issue, but rather an issue with the texture file itself, as trapdoors all share the same UV and models.