iPhone 14 Pro Max overheats during calls after iOS 18.2 update

Another thing that can affect heat on the iPhone is if your cellular signal is low. In that case, the phone needs to work harder to maintain the connection and can cause the phone to heat up a little.

After an update, certain related tasks including indexing may continue in the background, in which you may experience an increased battery drain and thermal temperature. When the update is fully complete, your iPhone will return to normal conditions.