My iPhone is overheating after iOS 18.1.1 update

Hi Nickiemaarie

welcome to the Apple (user-to-user) Community!

Re:" iOS 18.1.1 issues:

I updated my 16 pro max and my 12 pro max to iOS 18.1.1 yesterday. Ever since I updated, both phones overheat randomly, the screens freeze and become completely unresponsive. Not app specific, happens completely random. No temperature warning comes up at all when it happens, it’s literally the hottest I’ve ever felt my phone get."

There are various possible reasons why your iPhones could be having these issues

Your iPhones may need more time and space in which to re-index Spotlight and more after the update

See: If your iPhone or iPad gets too hot or too cold - Apple Support

Each iPhone needs at least 8Gb available storage / memory in which to operate smoothly.

See: How to check the storage on your iPhone and iPad - Apple Support

Unnecessary third-party (non-Apple) apps like ad-blockers, virus checkers, cleaners, and the like,

and even VPN, often cause issues ... if installed: try turning them off, or uninstalling them.

What to do: If your iPhone won't turn on or is frozen - Apple Support

Any third-party apps you find necessary may need updating in order to remain compatible with iOS 18.1.1.

If nothing above seems to be the cause:

if your phones have had a few days in which to complete update procedures, and the issues continue:

You may want to contact Apple Support: eg: using the link at top right or bottom left in this discussion thread.

or

You might want to let those who work behind-the-scenes at Apple know by sending feedback: They will likely not reply, yet your feedback will reach those who can make changes, if others are also experiencing similar issues: There's a web-form for feedback online: Feedback - iPhone - Apple

All the best :-)