Given Germany has some of the strictest privacy laws, I'm betting Klar is the honest version of focus. The fact that both exist separately makes me question Firefox's commitment to privacy.
Klar by Firefox is the German-language version and only available in Germany, Austria, and Switzerland. It includes the same features as the English-language app Focus by Firefox.
Why did we change the name/replace the app?
The publishing and media company Burda, which the news magazine FOCUS belongs to in Germany, is one of our partners. We therefore decided to replace our app "Focus by Firefox" in Germany, Austria, and Switzerland by "Klar by Firefox".
If you think it is suspicious you should be able to spot it in the open source repository. Otherwise see the other, and probably only, reason for the different name.