Generally, the quality of consumer goods from 20+ years ago. Everything is thinner, lighter, and chintzier now (unless you're willing to pay a lot, if you can even find something built as well as it used to be). Just some recent examples:
My wife and I were looking at souvenir beach towels on vacation; the towels were paper thin and rough.
Modern t-shirts wear out much much faster than stuff I have that's decades old. Even the screen printing wears off faster. One of my coworkers only wears secondhand clothing from the 90s through the early 2000s for this exact reason.
We bought a new metal colander, one that was well reviewed and boasted thick stainless steel construction. It's thinner and flimsier than the one we already have, and has already started to rust. The 15-year-old model is in great shape.
Our newer bedroom trash cans are thinner plastic (much, much thinner) than the similarly sized and shaped trashcan I have from when I was a kid.
Our $1500 custom made couch is showing wear after only 4 years. My parents have 40-year-old Broyhills in better shape.
I know there's survivorship bias when making these kinds of comparisons, but the older products weren't some ultra premium brand or more expensive alternative, they were mainstream products bought by middle-class families. This was just the quality you bought when you went to go buy things. It's concerning how badly quality has degraded.