I feel like we already knew this was caused by poor soil quality? Like, we fertilize fields with ammonium nitrate, urea, and diammonium phosphate. You'll notice there's no potassium, magnesium, zinc, iron, or copper being added back. There's less in every harvest.
The good news is that we already have the tools to fix this, in breeding, soil health, markets and policy.
There's literally nothing breeding can do to add micro-nutrients back to our food, and markets got us to this point.
The only solution is policy targeting soil health, and that's it.