I stand corrected! I have visited Catalonia quite a few times and never noticed they being homophones. In Argentina, or at least in Buenos Aires, they even teach you in primary school to pronounce the v using your upper teeth and lower lips (it makes it sound closer to f), and the b only with both lips. I'm very surprised to learn this, can't imagine pronouncing vacaciones as bacaciones hahah that's amazing, I wonder where this difference comes from.