80/20 is very high meat content for puppies. They will need to eat a lot of it to get them to put on weight and that then leads to loose poos as their smaller digestive symptons find it hard to process that amount of food.
If your puppy is underweight of the correct weight a 50/50 mix of carbs and meat is better. They will not see not much physical food and it will allow them to grow and be the correct weight without stressing out their digestion and hopefully less loose poos.
If your puppy is overweight then a 70/30 mix would be better.
However of course all puppies are individuals and will do their own thing just when you think you have the food sorted.