There is No UNDO to MacOS updates or upgrades.
You can never install OLDER MacOS over NEWER MacOS.
If you have everything backed up (two copies by different methods is often suggested) you can Completely ERASE your physical drive, deleting all files. then you can re-install the version of MacOS you like, provided it is not older than the version that shipped with your machine when it was new. Then you can Migrate your files from the backup.
-------
That is a lot of work, for something like Ventura that will become inevitable after a while.
Instead, Readers here can help you work through the issues with Ventura , if you like.