The wrong death message is displayed when being killed by a mob's smash attack.
Steps to reproduce:
Build a 4 block-high pillar
Summon a husk that can pick up items on top of it:
/summon husk ~ ~ ~ {CanPickUpLoot:true}
Give the husk a mace
Go into survival mode
Run
/damage @s 19
Get killed by the husk's smash attack
Observed result:
The death message that is displayed is "<player> was slain by Husk".
Expected result:
The death message that is displayed is "<player> was smashed by Husk".
Can confirm:
[media]