Jae

Switched from one two litre jar to three smaller ones and it solved most of this without changing the recipe.

A big jar is opened repeatedly over three weeks, and every opening introduces oxygen and warms it. Three small jars means two of them sit unopened and cold until you get to them, so week three tastes like week one did.

Keeping it submerged does more than people expect. The layer in contact with air is where it goes fastest.