Verschlimmbessern
Etymology
German, a blend of "verschlimmern" (to make worse) and "verbessern" (to improve). The word’s own construction enacts its meaning, jamming "worsen" and "improve" together into one self-defeating action.
verb · /fair-SHLIM-bes-ern/
To make something worse precisely through your attempt to improve it.
What it names
A maddeningly common outcome — the fix that backfires — in a single verb, capturing well-meaning meddling gone wrong.
Example
Every time he tried to declutter the codebase he only managed to verschlimmbessern it, trading old bugs for new ones.
Related idea
It is the personal-scale relative of a perverse incentive: that describes a system that rewards the wrong thing, while verschlimmbessern is one person’s helpful tinkering making the thing worse.