It is possible, even likely, that for some of those people it is not psychosomatic, but symptoms with a real physiological cause that has been not detected. Because it can be called "long covid" and so we need not explain it further, the actual cause is not found (or sought) and so symptoms persist. In many of those cases it is also likely that if, properly diagnosed, there is an effective treatment available. Sad. But typical of how medicine is done.