terminal weird behaviour

Did you also restore from a backup after performing the clean install? If so, make sure to restore from a backup made before the issue occurred, otherwise you may just be bringing the problem back again. Best to test before installing any third party apps and before restoring from any backup just to be sure.

Also, are you saying you pasted some commands into the Terminal app when this all began? If so, what were those commands? If any of them involved storing code onto a hidden partition or NVRAM, then I could possibly see something remaining behind depending on how the boot drive was erased. How did you erase your Mac & what exactly did you erase (or the procedure you used)?

What is the exact model of the Mac and version of macOS? You can get this information by clicking the Apple menu and selecting "About This Mac".

Give this a try: boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and test again.

NOTE 1: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

NOTE 2: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will insure a successful boot into Safe Mode.

What exactly does this mean: "My termination keep pasting every 10 seconds". Please describe in detail.

If you erased the disk, everything would be gone and you'd have to install a fresh copy of the OS. Did you install a fresh OS copy? If not, you're still operating with the "old" OS.

How exactly did you "erase", what procedure did you use in attempting to erase the disk?

With the Terminal application in Ventura, when launched, it retains keyboard and mouse focus until you specifically click on a subsequently launched application, or use the Finder's ⌘-tab to switch applications. If you copied something to the clipboard and did not deliberately switch away from the Terminal, then any paste operation will land in the Terminal as many times as you attempt it, and not in the expected application.

I have been using the Terminal for a very long time and mine does not independently do anything unless I explicitly click on it, followed by my typing (or pasting) input.