People who got covid vs other viruses. When you follow up with them 3 months later, there is no difference in symptoms between the groups. In other words, long covid symptoms are no worse than any other respiratory virus.
So is it covid causing the symptoms, or the pandemic? All signs point to the pandemic, and the response.
Every other long covid study are observational, and are likely confounded. Strongly recommend looking deeper at these studies. Very few have control arms, like this study does.