[2024] Math isn’t Mathing

Not sure if this is the right place for this - please direct me if I should put this elsewhere.

Board State: [[Venerated Rotpriest]] and [[Valiant Emberkin]] on the board. Cast [[Coordinated Clobbering]] targeting both creatures.

My Math says this should generate 4 Poison counters - Arena Math says 6 Poison counters.

What am I missing here?

Edit 1: Video below - able to repeat this scenario at-will. Video shows both expected outcome of single target spell on Rotpriest adding 2 Poison while Valiant on the board as well as the above mentioned “issue.”

https://youtu.be/U8zceUOKWnc?si=BiZFlt9insq9O5IO

Edit 2: Another multi-target spell targeting 4 creatures, adding 20 Poison to opponent.

https://youtu.be/e0WJr6nSmuU?si=aXRkatn-nTODWzk7

Edit 3: Theory proven? 3 targets 12 triggers! When do I get my gold plated bug finder trophy?!?

https://youtu.be/lpTGCpPyeL0?si=EOywDeQOtRtYcGvc