Disinformation, conspiracy theories spread with diseases in polarized, echo chamber times.

Science denial dates back at least to the time of Galileo, whom the Catholic Church found guilty of heresy and sentenced to house arrest in 1633 for arguing the Earth revolves around the sun.
And it’s likely always been around, in more recent decades showing up as denial that smoking can cause cancer, that human activity is a leading cause of climate change, and backtracking on trust in the established efficacy of vaccines. Even the re-emergence of people who claim the Earth is flat.