@LonM It cannot be the part of a shortcut because there're many ways to execute Vivaldi, the shortcut is just one of them.
Anyway, when you execute Vivaldi (or any Chromium-based browser), one parent process is executed, e.g. vivaldi.exe which executes many more child processes vivaldi.exe with various parameters, depending on what each child process should be doing (a renderer process, a GPU process, an utility process, a PPAPI process, etc.).
You can easily check it using the applications like SysInternal's Process Explorer or Process Hacker, just display processes as a tree and enable the command-line column.
The parent process has no command-line parameters (or it has any parameters you passed to it, no matter how it was executed), child processes have a lot of various parameters which are passed to them by the parent process (as it's actually executing them). None of those parameters matches what I see on the vivaldi://about page, so I'm not sure what exactly is displayed there, but it's most likely some sub-process executed by the parent one, so the only way to control those parameters would be through some Vivaldi/Chromium configuration, for example flags.
