Haunt+ poisonous spirit : 4000% of weapon damage is not applied

Is there a bug on Season 20 / Arachyr on PC

Haunt an enemy with a spirit, dealing 4000% weapon damage as Cold over 12 seconds. If the enemy dies, the spirit will haunt another nearby enemy.

4000% over 12 seconds. i.e. 333% per second.
Poison. spirit add 20%, i.e. 333%*1.2 = 400% per second.

The Arachyr set has no extra bonus to Haunt.

If you want to prove that it doesn’t work this way, please provide some evidence.