Possible fix: do nothing because this abuse needs a manual labor and so is throughput limited and every possible solution is going to be seen by someone else to be more buggy (delaying bonus until main product finishes would be confusing due to gui, not returning ingredients is going to cause ...

Thanks! Excuse me, I tried to look for it as it seems obvious enough but didn't find anything.

Steps to reproduce:

Take a building and fit it with productivity modules so that it has >100% productivity (for example, electromagnetic plant with 5 uncommon productivity modules). Put all of the ingredients in. Wait until the productivity progress bar completes and stop the plant before it ...