"Long COVID" is a grab bag comprising a bunch of things.
It includes a (probably pretty small) number of people with severe symptoms caused by COVID.
It includes a much larger group of people who are merely having a slow recovery from this unpleasant virus, but who will be fine after a while.
It includes people who have had COVID and are now blaming every health problem they have on that COVID infection they had a few months back (I was recently chatting with some mums at my local park--none of us have had COVID but we're all struggling with poor sleep, anxiety, menstrual disturbances and a whole bunch of other things that are being used as markers for "long COVID." If we'd actually had this virus, I am sure we'd all be describing ourselves as long COVID sufferers. As is it, we're suffering from pandemic-itis).
It includes people who suffer from crippling health anxiety that is causing psychosomatic symptoms.
It includes "mixed" cases, where there are some sequalae from the actual virus, but then anxiety is making the person experience the symptoms as worse.
I don't think many people doubt that genuine severe long-term issues can be caused by COVID, but the figures are almost certainly inflated.