Autumn started two days ago on FEI, and multiple weather areas are experiencing poor weather right now. (As an aside, the worst time to have poor weather is Autumn)
The 25% surplus is targeted across all seasons and ignores weather.
It would have been nice of them to account for the effects of seasonality, and not just a global average based on production alone... By my calculations, shared on these threads back when it was in the making, weather resulted in considerably greater rot (9% more, I think, but that's off the top of my head), as food, on average, stayed in warehouses longer become being consumed. And that was theoretical minimal rot, assuming all of the food had enough warehouses for it: something which is particularly untrue when seasons are factored in because it becomes somewhat onerous to build enough warehouses for the peak season. A greater "surplus" would have been nice to compensate for this. And this doesn't even cover the increased expenses of realms on thoses continents when they do try to build up enough warehouses...
As for the FEI stats shared here... you must also account that these are relative numbers: food production minus consumption divided by production. Thus, even if almost all realms are below the 25% mark, it's more than possible that those few above the 25% mark, just due to their size, balance out the average. That being said, I am not aware of which of these realms is large or not. Also, as others have mentioned, there are other factors, such as weather, to account for.