Gtk2 apps not following system dark theme

[nikgnomic]

@Kzer-Za

other GTK2 apps are affected as well.
for example, HexChat, which, if I’m not mistaken, is shipped with every Manjaro fresh install.

Hexchat has not been included in ISOs since Wynsdey 24.0.6 (2024-08-12)
Manjaro 24.0 Wynsdey released