No expert here but my first thought was they poured it super wet and didn’t let the water evaporate through the surface before they troweled. When you pour on styrofoam the only place for the water to go is through the surface and if you don’t let the bleed water evaporate than you trap it in by sealing it tight with a steel trowel. Im actually impressed that they could trowel a floor like that. I would do what Peter said and check for hollow spots. Also if this is a house I would get my money back and make them grind it down on their dime until you are satisfied but if it is a garage I would tear it.