In my experience the biggest source of tech debt is decisions made under time pressure that never get revisited. "We'll clean this up later" turns into "this is how it works now."

Also worth noting that what feels like tech debt is often just "code that does something different than what I'd do." Sometimes worth asking if rewriting is actually necessary or if youre just not used to the existing approach yet.

AI might help with routine refactoring but it cant make the judgment call about what should change. That still requires someone who deeply understands the system.