Indeed, the French taught in schools is Parisian French, but French as its spoken, e.g., in the south sounds noticeably different.
Parisian French isn't the same as Standard (Court) French, and it sound different in the South because It's only been the majority language for a century. It's super-imposed on top of another language's phonology. It's not a dialectal continuum thing.
Not wrong, but note that the difference is much less than language differences between different English speakers in England, even at short geographical distances.