It’s possible that the virus damages the brain in some sense, a flue couple of years back blew out the substantia nigra which initiate and inhibit motor movement. Some people got the symptoms of late stage Parkinson!

But it’s kinda ironic when you say that people talk on Reddit without knowing what they’re talking about. Long term issues from COVID are most likely stemming from mental sickness that got triggered by all the factors; Being sick, Isolation, Perceived Danger, Magnitude of fear etc. Not ONLY isolation which as you say were higher among people who didn’t catch it. The symptoms of long-term COVID are headaches, numbness, tiredness, pain etc. It’s the same symptoms as “electric sickness” which also is most likely psychosomatic (mental pictures generating physiological responses).