iphone 14 pro heating up while using imo

Activities involving heavy use of video rendering and graphics processing, of the display backlight, of processing, and of Wi-Fi and cellular networking, will all generate heat, yes.

If you have concerns about excess heat generated, you will probably want to discuss those directly with Apple, and potentially demonstrate the behavior to Apple.

Use the Support link in the lower left corner of this webpage, and chat or call Apple as available.