I was entering the food for our Memorial Day trip into my spreadsheet and discovered than many of my standard items that I have always used have reduced the amount in each package about 10%-20%. Beware that you may be getting a little less food and calories than you thought you were! I had to adjust my spreadsheet.
Yes, these practices have been in place for many years. Companies don't want to have to raise prices, so they reduce the quantity in the package, either by just pure weight or lowered item count.
Coffee and ice cream are two good examples of just less quantity in a 'bulk' item. Another example is how the Hershey fun packs of candies went from 10 pieces per pack down to 8 pieces per pack. Even multi-unit gum has gone from 10 5-packs down to 3 15packs.
If you've paid attention to the labels over the years, there are so many examples of this you'll find. And still prices have increased so much in the grocery store!