It is normal for Apple 13 to lose 4% after using it for more than 5 months.

Normal.

According to Apple's regulations, it is normal to keep the battery health above 80% within 1 year. If you feel that your health is declining too fast, you can use the original 5W charger to charge, because this charger has low power and is not easy to generate high heat when charging, which is conducive to protecting the battery.

Usually, when using the mobile phone, you should also be careful not to let the mobile phone run in a hot state for a long time, and don't wait until the battery of the mobile phone is completely exhausted before recharging. Users who use the iOS 13 system can turn on the "optimized charging" function in battery health, so as to keep the battery charge at about 80% all the time, which also helps to prolong the battery life.