Having 99% battery health after two and a half months is amazing. The only time you will start to see a difference is if it drops below 80%. You might have lost the time it takes to drain 1% from the battery. Probably less. Honestly I've had a phone that was at 78% battery health. Sure it was at about 1% at the end of the day, or maybe dead depending on how much I used it that day, but it is not bad and definatley doable. That was a iPhone X too which had a awful battery. Having the iPhone 14, you could probably be at 75% battery health and that would be completely fine. Probably the length of a new iPhone 12 pro.