What is a good English phrase for "produktionsbedingter Leerraum"?
The literal meaning is "an empty space caused by production" and tells buyers that the half-empty cookie box is a feature.
The technical term in the US is "slack-fill", however consumers aren't likely to know what this means. (In terms of potato chips and other vacuum-packed goods, this is also called "headspace"):
In order to explain this concept to consumers, you'd probably need to resort to a more descriptive sentence instead of a technical term. The other answers have provided some suggestions, although they do feel somewhat clumsy.
My additional suggestion: Product packed with empty space for transportation.
Such a thing doesn't appear written very often, and translating compound words tends to always produce clumsy results.
I would propose either
(short for "free space resulting from the manufacturing process")
As a label, perhaps