Video was too large, so I have this link for video evidence. A copy of the world is also attached for testing purposes
When moving up and down on the edge of a scaffold, different movement is experienced depending on the direction.
Downward movement seems to be much faster than descending the center of a scaffold, and the game seems to consider it as a freefall
Fall damage does happen when abruptly stopping on the scaffold
Falling/jumping off the scaffold, but then colliding back into it does cause fall damage (may be working as intended)
Because it seems to be considered a freefall, water does negate any fall damage
Upward movement is segmented as the player jumping up every scaffold block
The player is not affected by fall damage when moving up the edges of the scaffold
The player is hindered by other scaffolding blocks beside the scaffold they are traversing (not included in video)
I do use an alternative texture for scaffolds to make the center transparent. This should have no effect on duplicating the bug.
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Duplicate of MC-1133