I just found a paper in trying to figure this out, but it seems like the author of this study wasn't really looking at it as an autoimmune disease, but a post-viral syndrome like Chronic Fatigue Syndrome (ME/CFS) which is partially immunological, but not autoimmune. ME/CFS has been known about a lot longer than long COVID, and seems to be better (if not yet well) understood.

Reading though a lot of the sites with information on ME/CFS, it makes intuitive sense that long COVID has more in common with it than something like rheumatoid arthritis. I hope that long COVID brings attention to ME/CFS, or in studying similar diseases we're able to learn more about their common causes/treatments, or generally understand both better.

COVID is a virus, so not an autoimmune illness. Long COVID might be partly autoimmune

It seems like a mix. Part from organ damage, part from misbehaving immune response in some people

All I heard overpandemic was that COVID was triggering diabetes in people which makes sense because we don't know what triggers diabetes but one of the theories is it's caused by viral stress.

I bet any money they will one day find a genetic mutation like the one in BRCA2 that causes cancer.