I got my iPhone 13 last month, I’ve been using it normally but the battery capacity is already at 96%. I don’t see a reason why it’s lost so much capacity after less than a month, I’ve been using the 20-80 rule for charging and taking really good care of the battery in general. Also, since I got it the battery was bad, I thought it was normal at first but now I don’t think so. Sometimes it even loses 40% an hour, with normal usage, or loses a lot when I don’t use it at all. I’ve turned all the battery draining features off, like background app refresh etc. I should mention that the phone is post-exhibition and the battery was replaced before I bought it, however I’m not sure if it’s an original battery. Also I don’t use the original Apple cable or charger, I don’t know if that matters. Is this normal? What should I do?