inb4 “just use canvas cubes!” whatever! It’s a bug! I’m submitting it!
The top of a canvas wall (the part that gets bigger when you increase the X scale) scales the image’s height to the total height of that part of the model, and tiles the width. This seems to be a glitch as the other parts of the wall properly tile the height and width of the image 1:1.
Additionally, when the Y scale of a canvas wall is above ~232.8, the top of the canvas wall will go blank.