I just followed the steps in How to Make an HTML Signature in Apple Mail for macOS Catalina 10.15 and they work in Ventura 13.0.1 too. If you are doing this with Mail in iCloud drive, then the saved signature path (V4) is correct in preceding link. If not doing this through iCloud Drive, then the recent signature is the one that you saved with the current date, or if in the Terminal, the topmost signature when using:
ls -laht ~/Library/Mail/V10/MailData/Signatures
I did not use TextEdit as the editor and used Sublime Text 4, but any plain text editor can be used.
End result that I created: