It is because when you're facing a greater challenge, you'll go harder at it

But when it's at 0% it may be overwhelmed with the challenge and just give up

There is a significant amount of software involvement in that process for several years now, I believe, at least on iPhones. I believe it often tries to guess, based on past charging schedules, how long it will be plugged in, and set charging rates for optimizing overall battery lifetime. But that is my optimistic self hoping that is the goal 🙂

I remember about 20 years ago, the first time I realized that there is a subset of software that definitely can damage the hardware, e.g. fan control.

Your phone is asking you to retire it

That’s just how batteries work

Your phone is asking you to retire itYour phone manufacturer is asking making you to retire the phone

It's likely to do with the heat of your phone. If your phone is cool AND has a lack of charge, then there is tremendous capacity to shove electrons in (like easy to find space in an empty car park, using Elon's analogy). If the phone has more charge then it will charge less efficiently. After charging for a while it will be hotter and charging efficiency falls off. As to the specifics of why it got to higher charge, than the other 🤷 . Related, I love this Toyota mechanics explanation of Telsa's heat pump. https://youtu.be/7HC72p2gfuQ?t=185