THIS IS A FEATURE REQUEST NOT A BUG Didn't how to specify it on the website I think allowing for accent colors to be customizable in libadwaita apps (via portals I presume) would make the experience of using these apps on KDE alot better
Accent colors are already customizable in System Settings, and synced to all non-KDE apps that support it in our xdg-desktop-portal implementation. If GNOME apps don't see it, that's their issue, as far as I can tell. I recall that the implementation the GNOME folks have doesn't allow for arbitrary colors; only a pre-selected set of colors. If so, that would explain why whatever arbitrary color we set doesn't get respected there.