“Decoherence” denotes a process (losing coherence), not a state, but the article uses it like a state: “Well, for one thing, it creates decoherence.” The state would be “incoherence“ (the lack of coherence).

> the more decoherent a system is,

This should be either “incoherent” (lacking coherence) or “decohered” (having lost coherence).

That being said, yes, incoherence in a system is a form of technical debt, and use of AI for software development comes with a heightened risk of the system becoming incoherent.