Design debt is just deferred decisions.

Design debt gets talked about like it is a mess in a file. It is not. It is a list of decisions somebody chose not to make, sitting quietly until the day they all come due at once.

Where it collects

It collects wherever a screen was shipped before anyone agreed what the pattern should be. The second screen copies the first, the third copies the second, and by the tenth nobody can change any of them without changing all of them.

The fix is not a cleanup sprint. The fix is deciding the pattern the first time it appears, even when deciding is slower than copying.