"Thus, in Popper’s words, science requires testability: “If observation shows that the predicted effect is definitely absent, then the theory is simply refuted.” This means a good theory must have an element of risk to it. It must be able to be proven wrong under stated conditions."
"Here was the salient problem: The proponents of these new sciences saw validations and verifications of their theories everywhere. If you were having trouble as an adult, it could always be explained by something your mother or father had done to you when you were young, some repressed something-or-other that hadn’t been analyzed and solved. They were confirmation bias machines.
What was the missing element? Popper had figured it out before long: The non-scientific theories could not be falsified. They were not testable in a legitimate way. There was no possible objection that could be raised which would show the theory to be wrong.
In a true science, the following statement can be easily made: “If x happens, it would show demonstrably that theory y is not true.” We can then design an experiment, a physical one or sometimes a simple thought experiment, to figure out if x actually does happen. It’s the opposite of looking for verification; you must try to show the theory is incorrect, and if you fail to do so, thereby strengthen it.
Pseudosciences cannot and do not do this—they are not strong enough to hold up."
https://fs.blog/karl-popper-on-science-pseudoscience/