If there are mods, hard to tell. Ever if they seems not touch decay-system.
May be a bug, but can be mod related to.
Believe me, i love mods, and use them with pleasure and often, but i know that i can never be sure it’s not a mod without lot test in vanilla with the same results.
One of the reason, i try still run a “nilla” game beside, as test. I know not the thing each want do, just to say. Can be.