This is an eg of “don’t short change people in weight & volume (in sales)” the sin that the people of Saalih excelled out. It’s cheating & haraam. They need to make it clear, as the Hadeeth says “if you clarify, Allaah will place blessing in the trade”
https://www.bbc.com/reel/video/p0gfy0m7/shrinkflation-how-food-giants-try-to-trick-you