The iPhone12 supports 15W of wireless charging power and 20W of wired charging power. Both fast and slow charging of the mobile phone will cause damage to the battery life, and the impact of not fast charging is slightly larger than that of ordinary slow charging, but it is within the safe range; Bad habits during charging are the most harmful to the mobile phone battery, such as playing with the mobile phone while charging, which will cause the temperature of the mobile phone to rise sharply and seriously accelerate the aging of the battery.
In theory, the speed of charging, the slower the better, the least damage to the battery.