In trying to make a tool that hands out a liquid that you have to put into a container (which I found out was harder than it seemed at first glance, a little guidance in that would be helpful as I just hacked it in), I found out that putting a fresh liquid in an old empty bottle instantly makes it rotten.
Looking at the code and the save files, I think its due to it using the container’s spawn time instead of the liquid’s.
edit: found another bug, this time in the player save/load code disease.intensity is not saved