Created attachment 141160 [details] Example_app_launcher SUMMARY The new coloring introduced in KDE plasma 5.21 for backgrounds in some contexts does not play along with dark themes. Makes many things look out of place and harder to read due to using a too light background on white text. The color choices in earlier versions were a much better match (the color theme in the screenshots is "Obsidian", and looks much worse with "Obsidian Dark"). Affected things: - Notification pop-ups. - General pop-ups that show when hovering the mouse over things in the taskbar. - Background on the new applications launcher. In the first screenshot attached (showing the application launcher), earlier versions of plasma would use a dark gray color for the background of the application launcher, which was similar to the color of the taskbar (at least in breeze dark). Same in the second screenshot, the taskbar pop-up would use a similar color as the taskbar itself, which makes the text easier to read and looks better.
Created attachment 141161 [details] PopUp
This is just a bug in the color scheme itself. Color schemes should always use strong text/background color contrasts because the background may be made transparent, lightened etc, by things outside the theme's control. A lot of themes ignore this advice and set fairly low levels of text/background color contrast, which leads to problems like this. I would recommend reporting this issue to the theme developer in question.
The developers of this particular color scheme (“Obisidian”) already pushed an update. However, it wasn’t the only color scheme that was affected, and this was a sudden change that made color schemes that worked fine before now start getting more difficult to read. I think this type of changes would be better done by changing the color for a particular class in breeze rather than changing the class of the color used. Also noticed that a large part of the blame here was a desktop blur effect which suddenly was turned on in my config after a plasma update, despite having previously set it to “off”.