Reason 1: Variants with inconsistent major categories, classes, and nodes cannot share reviews. We sell a product A on the platform, and it has been selling well for several months. Then we want to make a color variant.

So we released a color variant B. A and B are exactly the same products, but with different colors. So we can merge them as color variants. After merging the variants, if the reviews are not shared and synchronized after more than 24 hours, you need to open a case to confirm whether the major categories, classes, and nodes of the two products are different. If so, contact customer service and inform the correct major categories, classes, and nodes, and change them to be consistent.