For example, if an icon theme contains only the audio icon named "audio-x-generic" then it doesn't get applied to any audio files. But if it's renamed to "gnome-mime-audio" then it does.
However, gnome-mime-audio isn't listed on that freedesktop page. The standard audio file icon name should be audio-x-generic.
Also audio-x-generic works in pcmanfm but not spacefm.
SpaceFM doesn't seem to follow the icon name convention described here: https://standards.freedesktop.org/icon-naming-spec/icon-naming-spec-latest.html
For example, if an icon theme contains only the audio icon named "audio-x-generic" then it doesn't get applied to any audio files. But if it's renamed to "gnome-mime-audio" then it does. However, gnome-mime-audio isn't listed on that freedesktop page. The standard audio file icon name should be audio-x-generic.
Also audio-x-generic works in pcmanfm but not spacefm.