Plonk - Decay attenuverter

So, i noticed (first day with this sweet module btw…) when i have no CV connected to the DECAY it will change the decay with how i turn the attenuverter knob.
Thats different then i am used to. I thought its only effecting the CV signal.

Is this normal ?

No one any idea? Maybe i was not clear enough with my description?
I am still confused about this. Why is the attenuverter of the decay acting different then the others ?