All new science starts with unsupported hypotheses. Going from "unsupported hypothesis" to "consensus established fact" often takes 10+ years. COVID and it's aftereffects are so new that the vast majority of claims are still somewhere in the hypothesis phase. Pretty much every idea about long COVID is still in this phase, and as sibling/cousin comments note it is an area of active research.

Science isn't static. It's contantly in evolution as people try to find justifaction for unsupported claims. Dismissing unsupported claims prima facie is fundementally incomaptible with the scientific method.