So from my understanding, the French and Prussians didn't get along too well, so I am confused as to why Frederick the Great named his palace in French rather than his mother tongue.
The long and the short of it was that Frederick II was a notable Francophile, albeit one with somewhat conservative tastes. The Prussian King both in public and private disparaged the German language as uncouth and lacking in subtlety. He often spoke French, although rather badly according to Voltaire. Sanssouci was one of several institutions Frederick established that were influenced by his Francophilia. The highest military decoration of Frederickian Prussia was the Pour le Mérite. Additionally, when Frederick II revivified the Prussian Academy of Sciences in 1743, he gave it a French name, Académie Royale des Sciences et Belles-Lettres, and mostly appointed French members to it. His theatre policies favored French actors and plays and he had scorn for German cultural development in this arena.
Frederick II was hardly alone in his Francophilia. The Enlightenment elevated French as a language and culture of civilization and progress. This enfolded such figures as diverse as the Russian Empress Catherine II and the US President Thomas Jefferson. Frederick II's favoritism of French also had tactical political uses as it made him an important patron within Central Europe. These cultural initiatives did set Frederick II and Prussia apart from the other German states including Habsburg Austria. It was also much easier for the state to control foreign cultural figures within Prussia as they were dependent upon state patronage; a German-language theatre troupe could always go into a neighboring German state if they chafed under Frederickian control, but a French one had less options.
Frederick II though did not let his cultural affinities for France get in the way of his geopolitical goals. Despite his patronage of Voltaire, Frederick II had a low opinion of the French of his era and saw them slipping from heights of late-seventeenth century into decadence. But for Frederick II, fighting France the state was not the same as fighting French culture and he privileged the French language over German despite his wars.
Sources
Adamson, John. The Princely Courts of Europe: Ritual, Politics and Culture Under the Ancien Régime, 1500-1750. London: Seven Dials, 2000.
Blanning, T. C. W. Frederick the Great: King of Prussia. New York: Random House, 2016.