>>Are people who had COVID actually more likely to have had significant periods of physical isolation in 2020 than people who didn't have COVID?
Any one who was diagnosed with having had COVID was prescribed to two weeks of total physical isolation, which is pretty unusual experience amongst people who did receive a COVID diagnosis. But yes it's possible that this did not have a significant impact. We wouldn't know without controlling for it.
>>In any case, unless you're claiming that social isolation causes a loss of taste and smell that persists for 8+ months, it's pretty clear that some symptoms of COVID persist for a long time in a significant minority of the population.
The two week physical isolation is one of many psychosocial differences between the two groups, and could affect one of many of the reported symptoms of long-COVID, some of which are much more likely to have a psychosomatic origin than loss of smell/taste, like the most commonly reported "long-COVID" symptom: anxiety.
Like any infection, long-term effects in some cases are very likely. The question is how many effects, and how common they are. Without much more rigorous studies, or some of cross-comparative analysis showing that COVID infections result in a markedly more severe clinical presentation than other infections, I think it's irresponsible to start sounding the alarm about some impending public health crisis from long-COVID. The very hysteria this could rouse could result in far more harm to public health, through more physical/social isolation and greater economic decline, both of which have a documented negative impact on health.
And the harm that a climate of fear can cause is already evident, from the massive increase in childhood overweightedness/obesity during the COVID era:
https://www.cdc.gov/mmwr/volumes/70/wr/mm7037a3.htm?s_cid=mm...
"Among a cohort of 432,302 persons aged 2–19, rate of body mass index increase approximately doubled during pandemic compared to prepandemic period. Persons w/ prepandemic overweight or obesity & younger school-aged children experienced largest increases."