If you’ve always believed that you have to allow leftovers to cool down before refrigerating them, you might be surprised to learn that this is a food myth.
If you want to save your leftovers, it's perfectly fine to store hot food in the fridge, and it's no more risky than letting food sit out on the counter for hours waiting to cool.
This leftover myth may stem from the fact that putting hot food in the fridge can raise the temperature inside of the fridge, which could then lead to bacterial growth in the food.
It would take a lot of hot food to warm your fridge above 40 degrees for too long, though, and the fridge will cool food much faster than leaving it out on the counter would.