I got an indestructible baby zombie plush doll when fighting a drowned with trident in survival easy mode on a completely vanilla Mincraft java 1.18.1 server. I did respawn within loading of both the drowned fight and the baby zombie spawn location

Steps to reproduce (difficult):

Die at the same time a drowned summons a baby zombie into a mushroom field (might happen in less specific contexts). This command should help to reproduce.

/summon minecraft:drowned ~ ~ ~ {HandItems:[

],Attributes:[\{Name:"zombie.spawn_reinforcements",Base:20000f}],HandDropChances:[0f]}