Most foods. Store brands are (nearly) always lacking in something. Be it tiny sized canned beans, or jam whose only flavour is ‘sweet’. That shit is cheap for a reason.
Doesn’t apply to everything (depending on where you live), some things you can’t cut corners on without advertising it. 2% Milk is 2% milk.
But largely, low cost food has been made low cost via haircuts and shortcuts.
Knew a fellow that worked for a food company - juices, nectars, preserved fruits, jams and compotes, baked goods with fruit, etc - that has a name brand. Most of the production is exported for so called "premium markets".
The largest supermarket chain here aproaches the company to have a few products made under their label. Not waterdowned versions of their recipes but completely new recipes or variations on the producers recipes.
Final product is as expensive or more to produce than name brand, which implies lower margins but still good money.
Supermarket product is not a waterdowned version but a completely separate product. If the end product is garbage, the supermarket gets the bad record.
I was comparing frozen diced veggies a couple of years back (in Australia) and noticed that the store-brand version was approximately 1/3 broccoli stems by volume, which certainly explained the cost difference.