In 2008 or so-Chinese baby "milk formula" manufacturers adulterated it with melamine
a toxic cheap industrial chemical high in nitrogen
The test for protein-was actually a simple nitrogen assay.
So they substituted cheap melamine for expensive milk proteins.
300,000 chinese babies were sickened-MILLIONS were poisoned.
Someone got a bullet in the head neck-but not great for babies.
15 years earlier they did the same trick with pet food-killed thousands of mainly USA-European pets
Same story substituting TOXIC ethylene glycol for glycerine-ended up in cough syrup and tooth paste

These supplement manufacturers will source proteins as cheaply as possible-they are all but unregulated.

A 10 beat drop in pulse??? 44 pulse older person???Don't know your age-guessing middle aged-but 10 point drop in pulse-from a supplement- toxicity/medication/drug effect-beta blocker?
Slow resting pulse is fine in a young healthy athlete-but a 50 plus person-44 pulse???? sudden drop??
Most MDs would want to rule out pathology toxicity-no matter your age-
I wouldn't take anything that did that to my pulse-

Guessing you pulse didn't actually drop 10 points-but if it did- from a supplement-you should be pissing in your pants.
Hell wonder if it is contaminated with a beta blocker????
A Beta blocker sure as hell could do that!!
Sounds like a drug effect!