Steps to Reproduce:

1. Summon a adult drowned without trident.
2. Change your gamemode to survival or adventure and let the drowned attack you.
3. Give the drowned a trident.

   /item replace entity @n[type=minecraft:drowned] weapon.mainhand with minecraft:trident

Observed Results:
The drowned will keep melee with trident, until you far away from it or the drowned stop attacking and find any target again.

Expected Results:
The drowned throw trident forward the target instead of stab the target with trident.

The Bug

This issue only happen underwater, it don't happen on land.
The adult drowned is more possibly to happen it, baby drowned is rarely to happen it.