While I haven't read the full report, I've never seen an assessment review the entire supply chain that is usually vertically integrated.
"costs go up" isn't some event that happens only because of drought/war/etc. It's true that resources are not always equally available, and prices can reflect this.
But when a supply chain is nearly entirely vertically integrated within 3 monopolies (oligopoly), there are plenty of costs that can be raised just because.
If there are 5 steps in the supply chain from farm to shelf, and the farm costs go up, every step in the supply chain can raise costs. If someone owns the entire supply chain, there are now 5 opportunities for someone to pay themselves, funded by the end consumer retail price.
It's painfully obvious that the lack of competition is encouraging unmitigated greed. They're using half assed myopic "studies" to suggest record profits aren't because of Greed since the last stage of the supply chain isn't exclusively where the gouging happens as if it's the only place profits can occur.