A lot of what was called science 100 or 200 years ago seems laughable now, some of it is still valid.
Well, a lot of theories which achieved traction in popular culture seem laughable now. That doesn't mean that they were accepted as proven by the scientific consensus.
As the scientific method took hold there were lots of things which had long been assumed which were eventually challenged but I can't actually think of a good example of something which was largely accepted as proven fact by science but then got completely reversed.
We knew of evolution long before Darwin showed it could cause speciation and demonstrated the mechanism. His ideas have been massively refined since.
The planets still exist, even if we got the way they move wrong at first.
Our conception of an atom has completely changed, but the atomic model of a century ago still explains most of Chemistry very well.
Stuff like Phlogiston, Aether, Race Theory or Lamarkian Evolution were never accepted fact. There were scientists researching those ideas but they took on a life of their own long after being disproven.
I think (as PPs have said) the problem comes in the application of Science. In medicine, for example; lobotomies, electro-shock therapy and chemical/surgical gender reassignment all became popularised long before the evidence was strong enough to support their widespread use. There was good evidence of the danger of smoking for decades before it was widely accpeted.
In all those cases it benefited someone financially to represent slim evidence as certainty (or the opposite for smoking).