That’s why these things should be regulated by the FDA and manufactured with validated systems with obligation to report any variance, etc, as any OTC drug company would have to (as well as Rx, of course).
The products they currently sell are not FDA approved. They have till May 2020 to comply.
I’m curious if their MFG line is cGMP compliant. It may be, but bad batches would say procedure Sops etc were either not in effect, not available or ignored.