How old is the iPhone 14?
On average, Battery Health / Maximum Capacity will decline about 1% a month. That is an average though. The battery might not decline at all for a few months, then drop 2-3% the next month. This is normal.
So if your iPhone 14 is 6 months old, the Max Capacity should be at about 94%. After 12 months, it will be at about 88-90%. Expect to replace the battery at about 2 years, or about 24 months from the purchase date.
If the battery drops to less than 80% Max Capacity and the iPhone is covered by AppleCare, Apple will replace the battery at no charge.