It's pretty common to have fuzz coat the louvers of the heat exchanger to the point of poor refrigeration. Sometimes it even requires replacing a part or two if too much excess heat builds up in the workings. That'd be my guess.
Proper refrigerator maintenance involves regularly cleaning the heat exchanger and surroundings if there is potential for dust/dirt buildup.
"It's pretty common to have fuzz coat the louvers of the heat exchanger to the point of poor refrigeration."
Here, it was a dish towel that fell behind the fridge.