DS1 is 9 so obviously several years under the age questioned. He has recently diagnised ASD, dyspraxia and dyslexia. He's been more relaxed and less anxious with limited social contact and 5 months of time at home playing minecraft. Home learning was a disaster (as it seems it was for all the families I've spoken to).
However he has to grow up knowing how to function in society. He may be content to be in his own quiet world, but long term that does him a disservice.
DS2 (7) on the other hand was frankly in a depressed mood by mid-June when the weather was shit and he hadn't seen anyone for nearly 3 months and hadn't been anywhere more exciting than for a walk/ to the supermarket. He flopped lethargically on my bed staring at the TV and got into stinking, rude, defiant moods. Fortunately as more stimulating opportunities have opened up he's returned to his usual sunny, cheerful disposition.
The school system certainly has its weaknesses, especially for children with additional needs (including emotionally). It's not that lockdown was a good thing, we need to improve the education system and treat children as young humans, not data sources.