Death spiral: When you keep creating products with no demand in the real world [1]. You create things, release things, nobody uses it, but by then, you're working on the next version nobody wants either.

Death spiral: Working on components of a larger project with no hope of ever integrating all pieces into a coherent final release. Everything gets incrementally improved in isolation, but nobody can figure out how to cut a product out of all the pieces.

[1]: Plenty of demand exists in the delusional minds of executives, PMs, and clueless employees though. It just doesn't match the real world.