the general consensus is that companies like the ones you mention, bulk purchase from "UGL" (not really UGL since its legal to manufacture almost everything in China legally) and just slap a label on it. China seems to be the only place to produce these peptides aside from compounding pharmacies that manufacture on an individual client/patient demand basis. GLPs in particular are a different story since US pharma have patents on them...
TLDR, buying bpc157 from Biotech, Limitless...etc most likely just gets you that "UGL" china stuff for up to 10x the price,
Please correct me if Im wrong. Would love to know more on this conspiracy lol