I don’t know anything about the specifics here, but here’s a 5 year graph of futures for live cattle versus beef:
https://tradingeconomics.com/commodity/live-cattle
If there’s collusion to engage in price-fixing by meat packers, I’d expect to see beef prices rising without a corresponding increase in cattle prices.
Beef prices did indeed recently start rising rapidly without a corresponding increase in live cattle prices.
But on the other hand, beef prices are also a lot lower relative to live cattle prices than they were during roughly COVID-19.
Oh, that’s a good point – missed that in the article. They did say that it started in 2015.