Battery indicator percentage error iOS14

Agreed. I have an iPhone Se 1st edition and it will do the following...

Battery goes below 52% (the lowest I've noticed) and I turn the phone off for the night.

Turn the phone on the next day and it says low battery of 1% at the main screen or shows the icon of the cord below an empty battery image and does nothing.

Turn phone off for a few seconds, reboot once or twice, and it will show around 20-30%.

Plug into computer and in very little time it's back up to the percentage it was before all this happened.

This has happened several times and it seems a temporary fix (at least for me) is to not let the battery drop below 55%. If I remember to do this then the issue never comes up.

Something to keep in mind, though it doesn't apply to everyone. The batteries are only able to be recharged so many cycles. In the past, this has translated into approximately 3 years of life. I just had mine replaced, and I it seems fine now. The Amazon lighting cable I'm using seems to only work in one direction though. I've also put a stopper in the port to prevent pocket lint from getting in there.

"Maximum Capacity 94% - This is a measure of battery capacity relative to when it was new. Lower capacity may result in fewer hours of usage between charges."

It gives no warning that anything out of the ordinary is going on with the battery.

What does it say specifically under “Peak performance Capability”?

However, that symptom is a failing battery. There are several different failure modes to batteries. An Apple genius bar can run diagnostics.

Unfortunately, the battery health information doesn't give you the whole story. You'll need the number of cycles it's been though as well, assuming it is the battery at all. Could be iOS, plugs, cables, maybe the battery was faulty from the beginning. I think the genius bar is the only possiblity for a final answer. Everything here is just guess work.

This should provide some useful information→About recalibration of battery health reporting in iOS 14.5 - Apple Support

Did you see my earlier post?

This should provide some useful information→About recalibration of battery health reporting in iOS 14.5 - Apple Support

Kinda hard to believe:

You have a very old device and maybe it's time to replace the battery.

No such thing as a one year old 6s. That model was released in 2015.

No one here would know.

Do you speak for everyone?

Do like 99% of device uses do:

Charge the device when not in use.

I got the same problem, I updated it now to version 14.3 but it did not fix anything. Later that day, I freed space to optimize my iPhone and the battery percentage came back to normal

100% agree. Between us, I believe we've tried all the options I can think of!