Not sure if this a bug or working as intended, but – Fruit spoilage rate in game files is set to 18 months, which is the same as preserves (According to Items/Resource Data files).
It seems like this may not be intentional (or may have a hidden modifier not present in those files), the loading screen tip “Fruit Trees planted by Arborists are a good way to utilize less fertile land but Fruit spoils quickly unless preserved” suggests this is not intentional.
Thanks for responding. I was checking the Items textasset file to see if I could reverse engineer spoilage rates using the LifetimeInMonths value (18 for fruit), but it looks like that means something other than spoilage/isn’t used by the engine in this way.