true, but only for pedigree dogs that are registered in the french "origin book" (Livre des origines français)
https://www.centrale-canine.fr/articles/le-nom-de-votre-chiot
the letters Z, K, Q, W, X and Y have been purged from the list, so it's the same letter every 20 years.
they say nowadays a lot of people also name their non-pedigree dogs using the letter of that year.
I also found some pages claiming that Belgium and Luxembourg have a similar system, but I have never heard of that until today.