Even if this is true (and I've never been able to find credible evidence it is), what we're seeing now is just the upper bound of sustainable plant-based food production. As they scale it up and take advantage of technologies like precision fermentation, all evidence suggests this will continue to improve even further. Compare that to animal agriculture, where thermodynamic limitations on increased efficiency are strong, and most of the options to increase sustainability come at the cost of terribly inhumane practices.

I've not seen this. What source do you have?

Please provide a source or delete your claim.