Marking with red colour both the animated properties (in Inspector) and the curves with missing properties (in Animation Window) is confusing.

2) How can we reproduce it using the example you attached
The red colour in these two cases informs about two different things:
Red in animated properties is just an fyi that the property value is being recorded - nothing to worry about here, while the red colour of curves that are missing a property (due to a component being deleted) are a warning signal.

If both "messages" are in red, it can be confusing. Can we make the missing curves appear in yellow? Since yellow is associated with warnings displayed in the editor.