seems like the output is rising in 2021, not declining http://www.fao.org/worldfoodsituation/csdb/en/

What exactly are you saying that it's going worse this year? There might be regions where production dropped (e.g. Canada plains), but overall we are higher than last year and higher than the average.

e.g.

USDA forecasts marketing year 2021/22 European Union (EU) corn production at 65.5 million metric tons (mmt), down 1.2 mmt or 2 percent from last month, but 2 percent above last year’s crop and 3 percent above the 5-year average.

from https://apps.fas.usda.gov/psdonline/circulars/production.pdf