The merchant can be summoned with a negative age which has the effect that he has the hitbox of a baby villager

The bug

The merchant can be summoned with a negative age which has the effect that he has the hitbox of a baby villager.

How to reproduce

1. Activate hitboxes with F3+B

2. Spawn a Wandering Trader with an negative age:

   summon minecraft:wandering_trader ~ ~2 ~ {NoGravity:1b,Silent:1b,Invulnerable:1b,NoAI:1b,Age:-1000000}

   summon minecraft:wandering_trader ~ ~2 ~ {NoGravity:1b,Silent:1b,Invulnerable:1b,NoAI:1b,Age:-1000000}

3. Watch the hitbox of the mob

Example

Here is an example in video: