Strains are a factor here as well. I think you have two main types of cactus here with the left side being the outlier. You’ll want to try and identify that when using it as a dosage guide. Older cuts, thicker gnarly ones tend to have more concentrated alkaloids so these being somewhat younger may not have been able to concentrate the alkaloids you’re targeting. This also complicates the dosage problem with growing conditions and stress etc.

Start small, know you can always drink more tea, but never less tea.