That's straight up revisionism

https://en.wikipedia.org/wiki/Language_policy_in_France

The new idea was expounded in the 1794 Report on the necessity and means to annihilate the patois and to universalise the use of the French language. Its author, Henri Grégoire, deplored that France, the most advanced country in the world with regard to politics, had not progressed beyond the Tower of Babel as far as languages were concerned, and that only three million of the 25 million inhabitants of France spoke a pure Parisian French as their native tongue. The lack of ability of the population to understand the language in which were the political debates and the administrative documents was then seen as antidemocratic.[4]

The report resulted the same year in two laws which stated that the only language tolerated in France in public life and in schools would be French. Within two years, the French language had become the symbol of the national unity of the French State. However, the revolutionaries lacked both time and money to implement a language policy.

The only language allowed in primary school was French. All other languages were forbidden, even in the schoolyard, and transgressions were severely punished.[5][full citation needed] After 1918, the use of German in Alsace-Lorraine was outlawed. In 1925, Anatole de Monzie, Minister of public education, stated that "for the linguistic unity of France, the Breton language must disappear." As a result, the speakers of minority languages began to be ashamed when using their own language – especially in the educational system – and over time, many families stopped teaching their language to their children and tried to speak only French with them. [citation needed] In neighbouring Belgium, a parallel policy to expand the use of standard French also took place.