Power consumption varies in different scenarios. The peak of power consumption for Ear (stick) is during calls.
It is normal that the percentage difference between the left and right earbud is between 0 and 10% when using them both simultaneously.
Upgrade your NOTHING X app to the latest version in the App store. Then go to Settings>Firmware Update.
Press the button on the charging case for 10 seconds for a factory reset.
If the issue cannot be resolved, take your device and proof of purchase to an authorised Nothing Service Centre for assistance.