The textures of purpur bricks , cut copper, Chiseled stone bricks [slabs stairs also] etc. have lines orientated incorrectly . Screenshots would help out
MC-242682
Pixels of certain blocks lined incorrectly
Resolved
Invalid
1
Literally a Can't Fix; if you fix it for that side, you'll only break it on the other side. All blocks apply the texture in the same fashion, even planks, and it cannot be changed without adding a different texture for each face, which is way over the top to fix such a miniscule annoyance.
See also MC-97303.