This happened to my baby around that age too, mummy 😊 He suddenly preferred latching and started rejecting bottles and even expressed milk in cups for a period of time.
What helped me was offering more water and dairy through food (yogurt, cheese, etc.) while continuing to breastfeed when we were together. It could just be a phase, especially at 14 months when they're becoming more opinionated 😅 As long as he's eating well, staying hydrated, and having wet diapers, I wouldn't worry too much ❤️