Are you using the Instagram app? It is documented that a bug in the app in combination with iOS 17 causes phones to massively heat up while doing basically nothing.
No, it's clean out the box (apart from our own apps, but as I'm running through XCode,, I know the app was killed), I ran the system update and that's it
Instagram's app is buggy, yes. It visibly increases battery consumption sometimes even if it's at the background. I keep it killed because of it.