Well, in theory, the Académie Française is supposed to be the authority when it comes to rules by which the french language abides. In practice, first, it only has authority in France, and not other french speaking countries, like Belgium, and second, only a small margin of people treat this seriously, most people don't care about what the Académie Française says about shit. For exemple, with the democratization of Internet in France, a lot of english neologisms (like spoilers, streaming, e-sports, etc) found their way into the french language, since they had no equivalent. The Académie Française did try to invent french equivalent for theses words, but nobody actually uses them outside of official documents (like court papers or governement texts) because people don't care.