One is that manufacturers deliberately form gimmicks for low design capacity.
The other is that the capacity calculation method adopted by your detection system or mobile phone manufacturer is wrong.
The design capacity is the theoretical capacity, that is, how long it takes you to play games, listen to songs, watch movies and so on.
The actual capacity is normal capacity, that is, based on the image quality and sound quality of playing games, listening to songs and watching movies, the power consumption is fast.
The design capacity is generally calculated as 50-55 minutes, and the actual capacity is 60 minutes, so there is a big difference.