Dec 21, 2019, 00:3012/21/19
Click on Palace, then 3rd tab, Statistics. In there, click on Food.
See if you can spot the cause:
By: > it took half away
I am assuming that you found half your food stock gone, not that your production per hour had been reduced by 50%.
And I am assuming that you didn't get attacked (check your mail icon for attack reports), nor spend it via starting a build / study / train.