I’ve actually seen two incarnations of it.

One version is that the Russians are pulling serial killer cannibals out of prisons to fight. I just saw this one within the past few days and I literally traced it back to one of the Radio Free(s) (all in the USAGM network)

The other version is that regular frontline soldiers are so desperate for logistics support that they are eating each other. That one was a while ago and I didn’t run it down