I know you all say when you first read the title that moon has a lower gravity so you can't take fall damage from a 4 block height logically. But the logical thing here is you should take fall damage with the same principal as the overworld but it should be multiplied by 4 because you can jump 4 blocks high. So if you take a fall damage by dropping from 4 blocks height, you should take the same amount of damage from a 16 blocks height on the moon. And if you die from a 23 blocks height drop then you should die from a 92 blocks height drop on moon...
