Amazon calculates a product’s star ratings using a machine learned model instead of a raw data average. The machine learned model takes into account factors including: the age of a review, helpfulness votes by customers and whether the reviews are from verified purchases.
My cat likes the flavour. She has been eating it a couple of weeks, and it looks like her fur is getting shinier. She needs to lose a kilo or so. So far, I see no change in weight, but it hasn’t been very long.