Faulty battery or Apple anti-repair anti-right to repair?

Just did a battery replacement for somebody last night phone said 0% when I plugged it in. Used an iFixit battery. He left this morning and shortly after unplugging the phone it died plugged it back in works unplug it it dies. Battery is not charging, is this a defective battery or is this Apple anti-repair since they sell the same battery for 5 dollars less? (after you find the super secret code and return the old one, if not it's 75 $ just to place the order). It did give the battery warning just like the previous model SE, unlike the previous model it never charged at all. I will find out more when I swap with a genuine battery. This guy seems to be plagued with phone problems or is it me, SE2020 Battery, screen, screen, SE2022 replacement phone, battery, now another replacement battery. On the upside I'm getting really good at doing phone repair.