If the marginal product of labor increases while the price of the product remains constant, the demand for labor will likely decrease.

If the marginal product of labor increases, it means that each worker is producing more goods or services. However, if the price of the product stays the same, the extra output from each worker does not lead to higher revenue for the company. This can result in businesses deciding they do not need as many workers because they can meet their production needs with fewer employees, even though those workers are more productive. For example, if a factory makes 100 toys with 10 workers and then discovers that those 10 workers can now make 120 toys without increasing sales price, the factory might think it can reduce the number of workers since the increased output does not change the income. So, even if workers are more efficient, the company may hire less labor if it doesn't see a financial benefit from the increased productivity.