According to the documentation, it appears that version 2 of the WebNowPlaying plugin (and probably version 3 too) does not support volume control at all:Thanks for this tip. I will try later.
https://wnp.keifufu.dev/desktop-players#caveats
The only solution remains the use of version 1.2.0 + the Spicetify tool
Statistics: Posted by xenium — Yesterday, 9:21 pm