So people kind of knew asbestos was harmful wayyy before it mostly stopped being used in 1979 (USA). But, it was still used constantly in many industries and ended up everywhere. What do you think is an example of something we find out is DRASTICALLY harmful 10-50 years from now? My guess would be screen time.
Teflon itself is technically “fine” if you ignore that it’s a forever chemical on its own. The chemicals used in the manufacturing, and the chemicals used to make a notoriously non-stick material stick to things are the big issues.
But like the other commenter said, even Teflon, despite its hydrophobic and non-stick properties, eventually wears out and spreads micro particles everywhere.