I have the same issue in version 1.14.8(stable) no mods
There is issue with inconsistent spoilage through cellar. jumping from 0.26 to 0.46 for no apparent reason. when container with 0.46 is picked up and placed in this same spot spoilage rate resets to 0.26
-outside temperature is below 6 degrees (issue appeared all year no matter time of day)
-there are 3 shelfs next to eachother, two show 0.26 one 0.46
-cellar is close to chunk border (around 3 blocks but is located completly inside
-chests seem to update to correct spoilage speed after you open them. You cannot update shelfs without destroying them and they seem to oscylate betwen those two spoilage speeds randomly.
I bought and played this game for a week really loving all aspects of it but that issue wont allow me survive throught winter and ruins everything i worked on
Found this bug reported: https://github.com/anegostudios/VintageStory-Issues/issues/765
If any additional info/testing is needed I'm happy to help