My 12.9 iPad Pro has 145 cycles since being made in January, 2016. Current battery capacity is 91%.
The thing usually gets stuck charging at 96%, and never goes any further, even though it's still in a charging state with the lightning bolt displayed next to the gauge. Rebooting it resets the gauge so that it says it's 99% charged, but it hasn't said 100% in ages. Cannot honestly remember the last time I saw it state "100%".
A couple months ago, when I first contacted AppleCare about it, the person with which I chatted said that never going past 96% charge is "normal since the battery only has 91% of its original capacity" (total BS explanation.) I complained to Apple about that explanation, BTW (I was sent a survey after they closed the call.) They really need to train their employees better.
I haven't yet bothered to escalate the issue with Apple, as I wanted to troubleshoot a bit more first, so ...
The device has been charged since purchase with the original 12W charger and cable that came in the box. I got the 29W charger and USB-C cable yesterday, hoping it would give better results, but it's just more of the same (except it gets to the 96% stuck state noticeably faster.)
I guess it's time to escalate with Apple support. As I was typing this message, the device, plugged into the 29W charger right after rebooting, went from 99%, down to 96%, with the charging indicator on. Not even doing anything. Display was off (I'm posting this from my phone.) What a pain. I think I either have a wonky battery, or something is wrong with the charging circuitry.
After seeing the numbers in this thread from others, it seems that losing almost 10% battery capacity in ~1.25 years is not very normal. Combine that with the charging issue I'm having, something's not right.