The real question is how much kills a shrimp and what is the KH of the tank water.
Dose makes the poison, not any amount of the "poison". Copper is a required nutrient for shrimp.
Like any drug, too much kills the patient, too little does not cure the disease.
KH is important when discussing any metal, in general, it's more toxic at lower KH's.
This is for free unbound metals though, chelation and other formulations make this more complicated. Chelation generally make the metals much less toxic per unit of ppm etc vs free metal ions.
A simple thing is to test the dosing, or for folks that already have been dosing and not losing shrimp to begin with, we already know it cannot be due to that.
there are 1001 and ways to kill critters in aquariums, we do not know them all or know the competence of every one we post with, however, this is not one of them.
Quite a few folks have these shrimps and dose these products at high concentrations without issues. For this to be the sole reason, we need to all have similar results.
I know I am adding TMG, CMS etc whatever chemical, and I am not having dead shrimp so I KNOW it cannot be due to that, it has to be some other issue.
Perhaps it could be a indirect thing, but it cannot be a direct issue as claimed.
Go back and look for another hypothesis why your shrimp are dying, have issues.