In 1.19.10 (or possibly 1.19.0 or 1.18.30-31) the vertical knockback that iron golems deal to all mobs was changed from 8 blocks to 3 blocks to match Java, fixing the first problem mentioned in MCPE-136616. However, for players there is still a gratuitous client-side adjustment that reduces vertical knockback by 5 or 6 blocks. This was added some time during 1.17, apparently as a botched attempt to bring parity to iron golem vertical knockback. It should be removed because it is not needed and it causes several bizarre effects.

Steps to reproduce

1. Open Vertical Knockback Desync.mcworld.
2. Stand at 0, -50, 0.
3. Equip a diamond chestplate.
4. Switch to survival mode.
5. Punch the iron golem.
6. Switch back to creative mode.
7. Have another player join and repeat steps (2) - (4) while you watch from about 10-15 blocks away.

Expected results

The player hit by the iron golem takes 3 blocks of vertical knockback and the following ensues:

• You see your Y coordinate go up from -50 to -47 before going down.
• You take 5 hearts of fall damage when you land at Y = -60 because you fall 13 blocks.
• In multiplayer, you see the other player get launched up 3 blocks then accelerate in a free-fall toward the ground.

Observed results

The player takes 3 blocks of vertical knockback server-side but this gets overridden client-side and the following ensues:

• You see your Y coordinate stay at -50 before going down during the fall.
• You take 2 hearts of fall damage, corresponding to a fall of 7 blocks, because the client subtracts 6 blocks from the vertical knockback. Vertical knockback first person.mp4
• In multiplayer, you see the other player get launched up 3 blocks then glide down slowly for 6 blocks before free-falling toward the ground. Vertical knockback 2nd player view-1.mp4