Hey @Rustymoo! Do you have any third-party accessories on your phone? This could be a case, fan, virtual reality headset, or a selfie stick. They could be causing your phone to overheat due to the extra power drawn by the accessory or by retaining the heat your device gives off.
Please try https://www.samsung.com/uk/support/mobile-devices/how-to-start-my-galaxy-device-in-safe-mode/ disables downloaded apps, themes and other launchers to help determine if one or more is causing conflict.
If that does not help try the diagnostic tool in your Samsung Members app.
A very last resort is to back up and factory reset
A Samsung Service Centre can take a look at your phone.
Daily Driver > Samsung Galaxy s²² Ultra 256Gb in Phantom Black.
The advice I offer is my own and does not represent Samsung’s position.
I have no affiliation with Samsung.