When Brush is broken in offhand, the broken Particle is the Item in mainhand

The Bug

Put a Brush in your offhand and brush Sus Sand, meanwhile hold the other item in your mainhand. When the Brush is broken, the Particle is the one in mainhand.

If your mainhand has nothing, it won't spawn Particle, not even play the sound "minecraft.entity.item.break".

3rd Party Source

https://www.bilibili.com/video/BV1aM411J76i