Hi all
After checking, the battery percentage on the screen and in the battery can not be 100% equal even in the ideal scenario or the brand new battery, the gap of the both side can be 1-4% difference. As time passes, the situation will become more obviously due to the battery aging. In that moment, the readjustment from the gauge will have an acceptable behavior which results situations like battery jump or percentage difference in 5 %. Sorry for any inconvenience it may be caused.
Besides, please refer to the screenshot below as the battery testing from my device.
*2 years old-ZenFone 5Z, Android 10 V99. Normally I use the device for device testing yet seldom turn it off.
**Charged over night to 100%, playing Youtube with 0% volume and 100% screen brightness