As others noted the this has little to do with quarantine and a lot with depression. However, there is a parallel between depression and quarantine, for me personally, it struck very hard, and I found myself questioning the value of my life up to the point where the thoughts of meaningless existence shadowed every good thing that ever happened to me.

Funny to mention but what helped me was Arthur Schopenhauer book "the wisdom of life", it deals a lot with a sense of meaninglessness and ability to overcome that. Do recommend.