Yeah my 15PM is as cool on 18 beta 7 as it was on iOS 17 and the battery is similar. I’d suggest it’s an app issue or some something edge case like too.Have you been able to pinpoint what's been causing this? I also have a Iphone 15PM for work but have no problems with heat or battery drain on 18.1 b2 or b1. I often wonder if the A17 pro is a modified overclocked A16----and some were borderline "quality passed" chips?
EDIT---have you tried "update all" in the apps? Maybe one of them is causing an issue?