In addition to generally worse battery life, which I suspect is temporary or until I tweak a few settings, the battery percentage being displayed on my Mini 4 is totally out of whack!
It'll say 80%, I put it down for 5 minutes and it goes to sleep and I pick it up again, and it says 65%. 30 minutes later with no heavy use it jumps from 65% to 40%. I plug it in, it instantly says 70% and charging.
It starting acting this way a couple of days ago. Yesterday I drained it (used it right until it shut off), charged it back up to 100% over night, and rebooted it. I'll see how it does today. So far so good. Battery at 97% with 40 minutes of use and over 5 hours of standby. Seems normal... so far.