iPhone's battery not charging beyond 80%
Why won't my battery charge over 80%?
[Re-Titled by Moderator]
iPhone 13 mini, iOS 17
It seems like that this is caused by optimized battery charging. This is meant to protect your battery. If you need it to have it charged full right now, turn off optimized charging temporarily to have it charge to 100%
On newer iPhones, you can also set 80% as the charge maximum that it will never charge further then that