My dog varies her food intake according to some mysterious signals I have no insight into. Most days she consumes 6-7 cups; but last week for some reason she decided that 3 cups a day was good. And no matter what her appetite is, she always grabs a mouthful of kibble and walks to another location (Not always the same) drops the food, and them eats the kibbles one by one. It's her way, so I let her alone.
As long as your dog is acting normally and not losing weight, I wouldn't worry about it at all. You'll no doubt have other issues/behaviors that crop up that will require your attention 😉
It's not the size of the dog in the fight, it's the size of the fight in the dog. Mark Twain