Mods, sorry I couldn’t post this in #faq-and-tutorials
Update: Apparently, this issue happens when using the RebornOS beta iso which is what I used. Devs will probably fix this before release.
If you’re having this issue, like I ran into when I was using Breeze Dark KDE theme, but Pamac is GTK so it wasn’t able to pick it up. You have to add a separate GNOME/GTK theme for applications.
To fix this issue, install the kde-gtk-config and pamac-tray-icon-plasma packages. There’s a more detailed write up with steps and screen shots available on - Theming | RebornOS Wiki