While it might seem fair to blame the company here, I would like to point out that many people with limited budgets (and this includes children receiving allowances, not just adults with a weekly cap on their grocery budget) would prefer a smaller portion of something to not being able to buy it at all. I am not talking about the soda can scam I despise with the 7.5oz cans when you can only buy a 12oz can in a twelve-pack in many places instead of a six pack now (this annoys the crap out of me). I am talking about the fact that inflation raises prices, and raising prices often prices customers out of things.
Companies don't like losing customers, and loyal customers who like certain products do not like being forced to choose between two "less full" sized products, or one product this week and two next week (or whatever; imagine being able to buy either a bottle of cold brew or a carton of creamer, OR simply having to settle for less of both).
Keeping the price roughly similar might seem like a scam but if you're some random person who really really feels their day sucks without something, would you like being priced out of it instead of disciplining yourself without any interference to merely have it a day or two less per week?
I am pretty sure few people really believe they are getting the same amount after a week or two of that smaller cereal box or whatever.