There’s a huge difference between how people view health care in general, and their own health insurance. According to the linked survey, in 2023 it was notable that only 72% of people had a favorable view of their own health insurance. In recent decades that has indeed sat around 80%, as OP claimed.

Again, that’s their _own_ insurance, while views of health insurance in general are quite worse, similar to how most people think congress is a shitshow yet rank their own representatives much higher.

It’s an interesting dissonance.