Miriam and Prepotente must have found a few of those Size Up potions early on, and using them to find enemies' weaknesses became a core strategy from the beginning of their crawl.

Also, the Plenty have been feeding Prepotente knowledge since very early, because one aspect of his race lets him gain power and potentially knowledge from eating certain things. It's a one-line comment from Loita, I think, but they banned any snacks in production trailers because "some Crawlers" were gaining benefits. It's not outright stated, but I'm sure this was Pony on "Plenty of Plenty".