x-sftpserver and x-shell not working properliy in URLs

Version: WinSCP 5.21.7 on Windows 10.
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Following the instruction:
Generate Session URL
Advanced site settings
I have the URL (SFTP) and made a URL-shortcut for easy access to my server, everything works fine. Pretty Good!

Lately, I tried to use a custom shell and sftpserver settings, also make it a url-shortcut, but I found that the x-shell and x-sftpserver in the URL don't work. Example:
Steps are like:

1. create a new session, fill in the username and pass
   
2. change Advance Settings, use custom shell and sftp-server argument.
   
3. save session
   
4. right click on saved session and generate a URL, copy it.
   
5. open system file explorer, paste the URL in the address bar and press enter.
   
6. successfully connected through WinSCP. Right click on the session tab, generate the URL again, the URL would be sftp://user:pass@servername/ without any shell or sftp-server argument in it. Yeah, not functioning in session either.
   

The WinSCP URL handler does not by default allow parts of the URL that could cause code-injection.

See also Generate URL session – Use only Shell: default