This issue is now 'fixed'. Changes are no longer saved to Config.wtf. The latest version of the addon will disable itself once it's run one final time.
A workaround for Details Damage Meter corrupting various World of Warcraft (Config.wtf) settings. (Gamma, audio volume among others)
The issue is explained here: https://github.com/Tercioo/Details-Damage-Meter/issues/479