Chosen Solution
After a month changing my battery, it still shows like these. Is it hardware or software issue?
Update (09/24/2019) Interesting. I just remembered I have a spare iPhone 6s. In the picture below, the top part where there’s a percentage is from iOS 12.1.1 and while the part with no percentage is after upgrading to iOS 13. Typical Apple, it’s so annoying.
That’s a software issue, being an aftermarket battery the iPhone can’t supply detailed information. Whether this is a hardware limitation or a deliberate Apple choice is questionable, but there’s nothing you can do about, you’ll have to live with it or replace it at an Apple service.
