The uranobacteria that is returned in the uranium carbonate recipe is affected by productivity when it probably shouldn't be. By this i mean the guaranteed return and not the 10% extra. This is pretty minor, but it allows them to be propagated faster than is probably intended, and in my set up meant they built up in a big stack that all spoiled at the same time, rather than a few getting cycled and refreshing their spoilage.

If i am not mistaken, this can be fixed by adding "ignored_by_stats = 1, ignored_by_productivity = 1" after the amount in the recipe. (I copied this from the Kovarex recipe).