Even if there is no change in battery behaviour to notice because it was like this from day one?
Besides, the battery in any consumer grade phone (or any other mobile thingy) is reasonable good, but never top of the line. Just a good compromise between runtime and production cost.
What’s to keep anyone setting up a production line to weaponise phones (that don’t have to be that cost effective in production) to make batteries with the same form factor than the original ones, but use better battery cells that can store a little more power in a little less space and use the saved volume for putting in explosives? Ending up with a battery that looks the same, weighs the same and has roughly the same electrical specs?
Also, who checks their phone battery in such a thorough way and keeps statistics?
(Yes, those people exist. Thankfully, usually in test labs and only a few out in the wild.)
Most people are conditioned to give the icon on the screen a glance and plug the thing in when they think they should. And that’s it because they have other things to take care of.
