Puppies are vulnerable if they dont get proper diet.

Dogs need minimums of many nutrients plus energy. Whatever their ingredients, most foods are formulated and processed to have enough of each nutrients the dog needs available with the excess of any helping to supply the energy needs. Thus fat and protein can vary widely and still provide the complete and balanced diet dogs need.

So you could look around at different foods with lower percentages of fat and protein with the bulk of the energy coming from carbohydrates. Beware of guaranteed minimums. You need the figures from analysis.

I hate to mention dogfoodanalysis since it has so much nonsense about ingredients, but as far as I know, the data there are no worse than out of date. So browse through looking for low fat and protein foods. Perhaps stick to the same ingredients as the prescription food.

Ignore the ratings. There is no science behind them.