Something strange just happened to me...

Last night I updated my iPhone SE 2022 from iOS 18.0.1 to iOS 18.1.1. Just before the update, as it was saying verifying update, I noticed it was at 27% so plugged it in. After the phone updated I noticed although it still said charging, it was at 24%. I brushed this off though and continued using it as normal until I got the message that the phone was at 20%. The battery was going down even though in the status bar it still seemed to think it was charging. So I unplugged it while I thought about the problem. When I unplugged the charger the status bar switched to saying not charging, and when I plugged it back in it said it was charging again but the charging tone didn't play and the battery still went down. That is until I found the notification I had left untouched that said the software update was finished installing. I pressed that, plugged the charger in again and it worked.
My charger and my phone both work as normal now but I was wondering if anyone else has experienced this fluke and /or knows why it happened? Come to think of it I have updated software while charging my phone and found the battery to be lower than it started at, but I guess I never paid much attention because I always cleared that notifcation immediately and then the phone would just keep charging.
Have a great day / night!