Some trees have generated with their leaves missing or in the wrong place. It happens to a few trees at once, and the cutoff of the leaves appears to be a straight border. I've tried recreating this bug by recreating the world with the same seed and finding the same coordinates; unfortunately, it seems to happen randomly and I can't recreate it consistently. The best way to seek the bug out seems to be to open a new world and keep an eye out for odd-looking trees. It seems to be different from the "stripped parts" bug and the issue where chunks from old worlds weren't deleted, since the effects of this bug are very localized and, rather than having the entire terrain of the chunk messed up, only trees are affected.