If you jump into a scaffolding Form a height of 3m vor higher you will not geht any Fall damage. Only when you reach the top or when you stop climbing.

Steps to reproduce:
1. Build a Tower made oft scaffolding (it should not be to low or it will be More difficult to do)
2.build a second tower that is far enough away Form the first. It should be far enough away that you Fall at least 3 blocks before you Land in the first tower.
3.Stand on the second tower
4. Change the gamemode to survivel
5.Now jump into the scaffolding as in step two and hold the jump button the whole time so that you can Start climbing inmediatly in the first Tower.
6. Climp to the top and see what happend

Observed results:
You geht only damage when you reach the top or stop climbing.

Expectet results:
You should geht damage in the scaffolding where you land

I don't know which platforms are affected,but i think they are all.