Calendar is causing my iPhone to overheat post iOS 18 update
The calendar overheats the device & it freezes and drains the battery.
[Re-Titled by Moderator]
There is a known issue with Exchange-based calendars and iOS 18 / 18.01.
If you are using Exchange then 18.1 might fix this for you. I had these same issues on my iPhone and iPad. 18.1 fixed it for me. Your device will eat a bunch of battery repopulating your calendar, but then returns to more typical usage patterns.