You’re storing your leftovers too hot in the fridge
Please don’t believe everything you read; cooling your food at room temperature before storing it in the fridge does have its risks. Bacteria is always on the hunt for warm meals to contaminate.
On the other hand, if you store warm or hot food in your fridge, the fridge’s temperature will rise, and bacteria will spoil all the food you keep in there.
Cool your food before storing it in your fridge but do it fast. The safest way to do it, approved by chefs, is using an ice bath.