it looks like half of the AI factions are starving to death and once some faction is starving they never get out of it in my campaign the only faction that had starvation and managed to solve it somehow was seleucid empire the rest just stayed like that untill they got eliminated
the food bonus should be like this IMO for every food building in Normal difficult AI get +25% on hard +50% on VH +100% on legendary +150%