GitClear does not run surveys. They instrument actual repositories and measure actual commit patterns. The 2026 update confirms the 2025 finding held — and in some dimensions got worse.
Here is what the data shows is happening to codebases everywhere:
Refactoring is dying. In 2021, roughly 1 in 4 code changes improved the existing structure without adding new behavior. By 2026, that ratio dropped below 1 in 10. Engineers are not making codebases easier to maintain. They are adding to them.
Duplication is exploding. AI tools are optimized to generate working code, not deduplicated code. They don't hold your entire codebase in context. They write the thing you asked for, and move on. Across 211 million lines, that pattern shows up as a 4× increase in copy-paste logic patterns — the exact type of debt that makes future changes expensive.
The mechanism is not laziness. It's incentive misalignment. Developers are rewarded for shipping features. AI tools accelerate feature shipping. The system is working exactly as designed. The side effect is that structural quality is being systematically deferred.
This is compoundable. Debt on debt. Every refactor you skip makes the next one harder.
LeadDev put it plainly: AI doesn't create bad engineers. It creates the conditions where good engineers stop doing the maintenance work that makes good engineering sustainable.
The question is not whether AI tools introduced debt into your codebase. The question is whether you have a measurement strategy that can show you where it is.
Does your team have a code quality signal that predates AI tool adoption? That baseline matters more than most people realize.