It should be identical to the Windows 11 taskbar without Start11 being installed.
That is the problem. The current color is Another Micrsoft fuck up that maybe Start11 can fix.
An app should finish in red state once it has a notification unless the app is doing something unusual.
Looks like you are thinking on the progress indicator of the buttons, red when a process stopped (And that is another fuck up of microsoft because they moved the progres to a tiny bar barely visible) but tha is not what Im talking about.
What I mean is the color from when the app needs attention and flashes the taskbar button
It was working fine, it used to be orange, but now, after a windows and Star11 updated at the same time It looks like this:

When a window needs attention, it flashes the button, but with this darker red is almost invisible and the blinking pases unnoticed missing important notifications.
As the OP asked, can Star11 have a setting to change this color to something visible?
And maybe also to change Number of Flashes (https://www.majorgeeks.com/content/page/change_taskbar_flashing.html)