I found a bug I think https://twitter.com/armagadon159753/status/918989470539636736 there is the possibility of taking damage of fall even jumping from 2blockd of height in snike. pmmp: last commit -ALPHA9 PHP: 7.2 Version: 1.2.2.3 os: 32bit - Android 5.1.1 thank you for reading this because I am not enough right to create an issue.
no, this is not a bug. You jumped UP starting from 2 blocks (rising 1.24 blocks), then fell 3.24 blocks.
According to the minecraft wiki an entity should not take damage from less than four blocks: Of course this may be different in PE but the page mentions nothing about it only applying to java edition.