Do you refactor enough? If you do, your OLD codebases are actually easier and faster to work with than your new ones.
If you use velocity as a productivity metric, you will almost certainly influence something other than productivity. Usually tech debt.
Friendly reminder: lines of code are a liability, not an asset. They're an investment you make to get features. Are yours worth it?
If you're trying to solve a social problem with a technical solution, and you're a programmer, you're likely actually procrastinating.