The bug

The hitbox for ladders is three pixels wide, despite other flat wall blocks (vines, glow lichen) only having one pixel wide hitboxes.

How to reproduce

1. Find a wall directly above a block with identifiable pixels
2. Place a ladder on this wall, noting the hitbox
3. Place a vine on this wall, noting the hitbox
4. Place glow lichen on this wall, noting the hitbox

Expected results

As all of these blocks are flat planes which cling to walls, their hitboxes would be the same (one pixel).

Actual results

Only vines and glow lichen have a one pixel wide hitbox - ladders have three.

Further notes

I've tested sculk veins from the 1.19 experimental snapshot as well, and these indeed also have the correct one pixel hitbox.