Catalina runs hot

The problem is with your computer, not specifically with Catalina.

Use Activity Monitor to Kill Runaway Processes

     Use Activity Monitor on your Mac

     Runaway applications can shorten battery runtime, affect performance, and increase heat and fan activity.

You should backup your files, erase the drive, and reinstall Catalina.

Install El Capitan or Later from Scratch

If possible, back up your files.

1. Restart the computer. Immediately, at or before the chime, hold down the Command and R keys until the Apple logo and progress bar appear. Wait until the Utility Menu appears.
2. Select Disk Utility from the Utility Menu and click on the Continue button.
3. When Disk Utility loads select the target drive (out-dented entry w/type and size info) from the Device list.
4. Click on the Erase button in Disk Utility's toolbar. A panel will drop down.
5. Set the partition scheme to GUID.
6. Set the Format type to APFS (SSDs only) or Mac OS Extended (Journaled.)
7. Click on the Apply button, then wait for the Done button to activate and click on it.
8. Quit Disk Utility and return to the Utility Menu.
9. Select Install OS X and click on the Continue button.

Once you have a properly working system, you can restore your files from your backup. If you install third-party software, then be sure to only install software that is compatible with the current version of Catalina. Also, if you haven't done so already, then locate and remove all 32-bit software. You can replace it with 64-bit versions, if available.

Internet Sharing is a feature enabled in the Sharing preferences panel. You might use it in order to share your Ethernet connection via Wi-Fi so your iPhone can use a Wi-Fi connection where none is available. It should not be running so high. Open the Sharing preference panel in System Preferences and uncheck the Internet Sharing option.

You did not mention if there were other processes running at high CPU times. If you haven't done so, then change the sort order by clicking in the %CPU column to sort in descending order. If the first two or three processes total 100% or more, then that is why your system is running hot. If these are running apps, then Quit the apps.

Read the links I have provided and the one provided by BobTheFisherman. They will help you better understand how to use Activity Monitor to fix heating problems caused by crashing apps or processes on the computer.

Some things to try:

Keep your Mac notebook within acceptable operating temperatures - Apple Support

Read through the two article links I provided. Should explain it all.