Put it on the record
Your report appears right away, marked Reported, until we or other shoppers back it up. A clear photo of the size printed on the label is the best proof; without one it's labelled as having no proof yet.
Adding the size it used to be. Enter what it was under Was. An old pack you still have, an old photo, a screenshot of an old store listing or a flyer is the best proof; add it under Old pack.