For the record, three of the protective antibodies to COVID are anti-SARS-CoV-2 spike IgG (nCoV S-IgG), anti-SARS-CoV-2 spike receptor-binding domain IgG (nCoV RBD-IgG), and anti-SARS-CoV-2 neutralizing antibodies (nCoV NAbs).
Two of these are IgG. IgG is the most common major immune system subclass in the body. I'm guessing these morons misinterpreted a positive immune response for something more nefarious.
Or they're relying on sources like VAERS which is a common anti-vaxxer mining ground. It's not a data collection center and they explicitly state as such. But that never stopped the anti-vaxxers.
Or they made the error of attributing causation of a disease from an abnormal lab value. Even if certain lab markers (like IgG4) have been correlated with a disease, it is not like some light-switch that guarantees a diagnosis.
If you knew anything about medicine, you'd know that.
My guess is JPW never dug any deeper than "Yup! Sounds just like what my gut told me!".
4th link - a synopsis (not the actual paper) that has nothing to do with correlation or causation with some generalized chronic inflammatory condition. An elevated lab marker may mean a lot of things or nothing at all. They didn't even mention chronic inflammation. The 4th link has to do with COVID vaccine efficacy and IgG4.
JFC You didn't actually read any of these, did you Yav?