Having worked for a French multi-national I learned a bit, especially fluent in saying:
“Je ne parle pas français” with no accent and much to the surprise of those hearing - who just assumed I was messing with them. But we were in the Caribbean and the island of Martinique and tried to get something to eat at the local market. The woman taking orders had an incomprehensible accent but fortunately we were sitting next to a couple from Paris who assisted with the order.
When I asked her if the waitress had a strong accent, she said “it’s not Parisian” - which I laughed loudly knowing how snobbish they can be.
Similarly, our very first visit to Paris years ago, we went to a restaurant a friend had recommended. In true French style, a table for two meant sharing a table for four with two strangers. During the meal, our neighbours seemed to pretend to ignore knowing any English when asking for the salt and pepper. But at some point, they must have overheard our conversion and asked in broken English if we were from Sydney. On saying yes, they both gushed fourth in perfect English saying they’d lived in Double Bay for a while…
These days, you can’t stop the French wanting to speak English. A whole generation has moved on.