Flat Earth has not been shown to be an infectious disease. Believing Flat Earth generally does not endanger anyone’s life unless you are working for a space agency or NASA? There was that one flat earther that got himself killed trying to launch himself in the air to prove the Earth was flat.
It’s pseudoscience not just because there were unverified claims. But because they in a Freudian slip call it an ideology and not a science proving that they are not being scientific about anything. But rather ideological. Therefore not actual science. They were disproven on many things like masking etc. But no matter how many times it gets posted or linked. Certain types of people ignore or just refuse to believe.