The substantive claim against PFAS is that they're very persistent in the environment, can bioaccumulate, and end up in places we didn't anticipate (e.g., in the rain). This is a good argument for scaling back.

Separately from this, there's some science to suggest that PFAS are harmful to humans, but at doses very much higher than experienced by the general population. Many of the headlines about PFAS being detected in weird places involve parts per trillion, and at that level, no health impacts have been demonstrated. Even for lead and ethylmercury in water, the norms are in parts per billion.

Then, there's a cottage industry of anti-progress doomsayers who want to equate it to a handful of big environmental missteps of the past, so the lines get blurred. Same as with microplastics, where you're bombarded with headlines about them being found in random places and being vaguely bad for you.