Hi everyone. I own a 2011 White MacBook running OSX Sierra 10.12.6, and an iPhone SE running iOS 10.2.1. I do not wish my upgrade firmware to have my battery life negatively affected or have the phone slow down. Apple just rolling out iOS 12.3 today further brings concern. I had the iPhone SE battery replaced back in December 2018 and it has 95 charge cycles on it according coconut battery. At various points within a 48 hour period, coconut battery has said my iPhone SE has 95% design capacity, to 64.1%, 56.2%, to 82%, and then now to 13.5%. I did a soft reset on my iPhone SE and I also drained the battery to zero by running a Youtube video at full brightness and with the flashlight on and charged it back up to 100% in low power mode to try recalibrate it before getting the most recent reading of 13.5%. Can coconut battery readings fluctuate like this? The readings are also consistent with iMazing and the third party Battery Life app that still runs on iOS 10.2.1.