You were not confined. At any time you were free to leave what ever constraints you placed on yourself. Moreover, your place of self-isolation was not deliberately stripped of sensory opportunities.
Did you stay in a dark, cramped, windowless room for months? It's pretty insulting to think that lockdown is anywhere near being stuck in a 2m x 2m space for months...
Holy moly. I hope this is some dry jesting. Comparing living freely in a home of some kind. Even a car. Comparing it to solitary confinement is so wrong.
I thought at first you were mocking everyone acting like stay in orders were any thing like solitary confinement. But your last paragraph throws that notion off.
Using that definition muddies the definition a lot.
4 years is definitely cruel and unusual imo. 15 days is whatever.
I just think they should have soft things and light etc in their cell if we're going to continue using that. A comfortable place.