Dan Bell's Dead Mall Series is oddly depressing and he often gives some back story into their declines.

https://www.youtube.com/playlist?list=PLNz4Un92pGNxQ9vNgmnCx...

A common theme appears to be either struggling footfall or the fact that what I guess are major US anchor stores (Maceys, Sears, KMart) going through tough times. Once the anchors move out, it becomes difficult to run the mall.

Interestingly, in one video, the Mall was half turned into offices, and it had a thriving food hall which I thought was a great idea to keep it relevant. No other dead malls in the series appear to adapt so they become ghost towns then abandoned and later demolished.

A shame really.