SoC sudden drop?

Explanation: car wasn't actually charging overnight due to operator error (daughter asked to plug in, didn't do it properly). Kia app quite often shows old data, with no timestamp, leading my to look at a stale SoC from yesterday.

We have EV9 Land, ~6500 mi and live in northern New England.

Car was plugged in to our L2 charger over night and got up to 80% (the max that I set for AC charging).

This morning, my wife was getting ready to leave and unplugged the car (still powered off) in anticipation of her departing.

A few minutes later, I happened to look at my phone and see the SoC at 78%, which I thought was a little surprising given that it was off and had only been unplugged for ~15 minutes.

Half hour later or so, I get a text from my wife on the road that the SoC was at 56% after only driving maybe 15 miles! She continued the remaining ~10 miles to her destination and it ended up at 49%, which is not as precipitous.

It's cold out; teens (F) overnight and in the low 20s now, but not incredibly so.

What gives? We did just apply some software update... is it possible the SoC reporting is buggy? Where did those ~25 kwh go?

EDIT: formatting

EDIT 2: Probably user error explains all of this.