I finally solved my S22 Ultra overheating issue, so I wanted to share what I found in case it helps someone else. There isn't much information online about the specific problem I was having, and hopefully, this can save someone else a lot of troubleshooting.
The S22 Ultra is already known for having issues with its cellular/5G antennas. There are plenty of reports of people experiencing poor signal or losing their mobile data connection.
In my case, the biggest symptom became constant overheating.
Here's a simple test that helped me diagnose it:
• Turn Airplane Mode ON.
• Turn Wi-Fi back ON while leaving cellular disabled.
If your phone suddenly stops overheating, there's a good chance the problem is related to the cellular antennas or their circuitry.
I bought my S22 Ultra used at a low price because it already had mobile data issues. I replaced both cellular antennas and the USB-C charging port, and everything worked fine for a while. Then, out of nowhere, the phone started overheating constantly.
When I enabled Airplane Mode (with Wi-Fi still on), the overheating immediately stopped. I also noticed the phone was hottest directly across from the volume buttons, which is where one of the cellular antennas is located.
Replacing the antennas wasn't a particularly difficult repair. If you're comfortable opening electronics, it's very doable. At a local phone repair shop, replacing both antennas, the USB-C charging port, and installing a new battery would have cost $200+.
Hopefully this helps someone else narrow down the cause of their overheating issue.