I'm not sure if I'm weird or what but for me it only complained about me having a non-standard name and address and that I didn't have enough funds in the Steam wallet it kept trying to use.
I guess I just got super lucky that I got the transaction to go through after only a minute of trying, a literal minute before the announced 10 am Pacific time opening.
I don't believe that because this isn't about capacity calibration, but more so that the battery voltage is almost constant between about 20% and 90%, though varies by battery type, and no matter what, the controller can't exactly know how much the battery is actually charging and discharging so it has to guess the current state. I've seen this happen on a Dell XPS laptop I have from work, I manually set it to limit charging to 80% since the built in "Primarily AC Use" mode cycles it around 95%, and it doesn't do the occasional recharge to 100% by itself, so about once a month it would jump from whatever percentage it was at to 7%, even from 80%.