>>41360263
https://archive.org/details/InterviewWithRabbiAbrahamFinkelstein

This has been known for a very long time. Logistically, there isn't enough beef to meet demand. So they cut (mix) the meat with all kinds of meat. Human, horse, rat, pig, whatever they can get quick and cheap. This has been going on since the industrial revolution, and probably long before that even. Look up what butchers use to mix with meat back in the 1700s before regulations were enforced and how appalingly unhygenic they were. Not much has changed.

Pic related. IYKYK.