Xfce Panel > Dark Mode: Menu Buttons not themed

[newhoa]

I noticed when using Xfce Panel's Dark Mode, the dark style is not applied to the Pulse Audio Plugin media buttons.

Greybird: 3.23.2
Xfce Panel: 4.17.3
xfce4ui: 4.17.7

Greybird, Xfce4 Panel Dark Mode On:

When switching to Greybird-dark, it does apply.

Greybird-dark, Xfce4 Panel Dark Mode On:

[newhoa]

Hmm, also, the button style is slightly different (darker, flatter, and less padding) if Panel Dark Mode is Off and Greybird-dark is selected.

Greybird-dark, Xfce Panel Dark Mode OFF: