I know there is a message when opening a project, where it says when there is a missing plugin and on which track. But it would be easier to spot, if it would be in its dedicated color (green, or red?).
Especially when there are more plugins missing, the list at project startup could be long, so you’d have to note how many tracks are affected.
Just having a better visual feedback would be nice
Its maybe a bit exaggerated, but to get the point: