From https://www.law.cornell.edu/uscode/text/15/6602:
Now you have to argue that losing 1% of battery per hour of sleep is a significant and substantial issue that severely impacts the usability of computer. I don't think you would have much chance here.
So far, the factual basis is that there is a very minor issue and that Apple has promised to fix eventually. I don't think they have to do anything more than that according to the law.
Lol. Um, yeah it is a material defect. I’m glad you can Google, but can you think? Or is all you know is what the big corporation tells you? You know their word is not binding, right? OP has no obligation to wait for their fix. I wouldn’t. The Apple Store will give a refund most likely. I brought back an iPhone 6s Plus a year and a half later when it started performing poorly. A smile and an explanation goes a long way, but if they don’t want to budge, so does a certified letter.