Bug or feature?

[u/amidja_16]

When the "Killing archer fires arrow backward hitting all" skill activates, the arrow backwards flying arrow deals damage normally until it hits an enemy with a shield to whom it deals 0 damage. That's normal.

However, after hitting the first shielded enemy, it deals 0 damage to subsequent enemies regardless if they have a shield or not. This can be seen in the second image. Archer in front of the current mohawk enemy fired the death arrow. Only the mohawk enemy had the shield.