I quote in full the proposal I made on the Kubuntu task, but it is better to propose it upstream.
What do you think?

Hello to all. It is the first time I write here and try to propose something, so if I have done something wrong, please let me know and I apologize in advance.
In recent versions of Kubuntu, the color of the panel theme has changed to too light black, it would be nice to have a darker / shiny black, as it is on Ubuntu's gnome shell panel, it looks more elegant. Thank you.
The black panel of Kubuntu:

The black panel of gnome shell on Ubuntu: