I am not sure 10 days isolation (even a few bouts of it) would have that effect
Are you being deliberately misleading on the 10days, I was in no shielding and doing absolutely as much as was legally possible, and I spent most of last year isolated from people.
Isolation is not 10 days at home occasionally, isolation is not being able to attend school, work, support networks, not able to meet friends, not having incidental meetings with strangers (the stereotype of the lonely pensioner talking for ages to the cashier) these are things which are linked to poor health outcomes, and very strongly linked to all of the mental symptoms.
Then we also have the physical effects of the same isolation, less or little exercise, little active travel etc. all of those can either cause physical symptoms or reduce the management of other chronic conditions that people have.
The short term full isolation is more heavily linked to an immediate drop in health markers (increased stress, lower vo2 kinetics) rather than the long term symptoms.