It varies, it usually ends up happening while my phone is idle and asleep so I don't always see it. I have seen the apple logo briefly when it does it. But it was happening on wired charging, MagSafe charging and Qi charging. I knew it was rebooting because I would wake up in the morning and had to enter my PIN and my lock screen widgets were locked. I also had an entire page of panic logs.
Gotcha thank you.
Hmmm, I can totally understand being concerned but it doesn't sound like a hardware issue. Might be worth getting a replacement unit to isolate especially if you got other gripes with your unit.
The pin code ask
is an indicator of a reboot.
I've seen the wonkiest things on x.0 releases, in logs too, I recall I think iOS 6.0 of all releases had random reboots opening camera app. It was startling but it got worked out by .1 or whatever. But almost no one reported on it I guess cause people either dont care or shrug it off.
I think... iOS 11 or something had a similar reboot issue overnight iirc. definitely one of the post -iOS 7 releases that wasn't the dumpster fire of 7 which had its own onslaught of issues, including reboot haha
if you saw a single color flash as soon as or minutes after putting on the charger, I would be alot more concerned but not going to fault you for still being.
I even saw my series 7 just randomly reboot on watchOS 8 once or twice this year, something I have never really seen on a watch.