Heating issue on iPhone 13

The iPhone will get warm under various circumstances, heavy usage, charging, etc. however it has a temperature sensor and if the temp gets above safe operating conditions it will give you a notification. I would not be too concerned about it unless you get the warning. Nonetheless if in doubt you could have it tested at an Apple Store.

Many users who have updated to iOS 16 and above must have a similar issue if the issues stated by you are due to the iOS.

Unless you state what the issue is many in this forum may not be able to respond positively to the issue you are facing. 

With the limited information that you have provided, It is hard to even guess the problems faced by you. 

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Please re-post with detail so that someone else can help.