New Laptop Battery - should I be concerned about its life?

My sons laptop battery needed replacing, so I purchased a (ostensibly new, legitimate Dell OEM) battery from a local supplier, however the battery behaved in a way I don't recall seeing before (in fairness, I don't often change laptop batteries). The battery is a 42Wh Lithium Polymer battery, Dell code WDX0R. Immediately when the battery was plugged in the laptop - a 2016 Dell Inspiron - advised the battery was at 48%, however by the time it started and installed Windows updates - 2 or 3 minutes later, the battery level was 7%. According to the battery report the capacity somehow jumped from 4

Question by davidgo on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.