What is Shrinkflation?
Shrinkflation is when a company knows that if they increase their prices, they will lose customers, so they make the product smaller or inferior in quality instead. When they do this, they can keep the price the same.
A famous example of this is the Toblerone bar. When the chocolate company couldn't raise the prices without lowering demand, they made the flat parts of the chocolate longer and the triangle parts thinner and smaller in height. No one noticed, and they could increase their profit margin without disappointing their customers. Companies like M&M can do it because no one counts the individual pieces, and they don't change the packaging size.
This happens a lot with hot sauces and other condiments. It also happens with drinks; Gatorade does it by changing the shape of the bottles at the same time as reducing the volume of liquid in each bottle. How they change the shape makes it extremely difficult to tell the difference unless measured with a scale. Companies can only do this so much before raising prices. Still, if you start looking for it, you will see it everywhere. When we were kids, Pringles were almost twice as big for each chip :(