Hello, I would like this functionnality in the following release of KDE. Enable users to assign unique color themes to specific applications for a more tailored workspace. This would enhance focus, accessibility, and workflow by allowing distinct looks for productivity, entertainment, and system tools, aligning with user preferences and improving overall experience. Thanks. Camille Demoulin
Some apps already do offer this. The ones that don't need to have the feature implemented for them individually, on an app-by-app basis I'm afraid. So you would need to open new bug reports for each app (and only for KDE apps, since this is the KDE bug tracker). You can also kinda sorta get this with window rules too, which allow assigning arbitrary color schemes to windows' titlebars. But not to the entirety of them, only their titlebars.