Cubase wants me to save project twice?

In my latest project Cubase “asks” me if I want to save the project, every time I close it although I already saved it.

So my rutine is to save and to quit, and nevertheless I get this question.
How come?

This is typically caused by a VSTi or plug-in that is continuously generating a changing value even when stopped. An LFO for example might be sweeping a filter even while standing still. Cubase sees these as changes (even if we might not) and asks to save so it can capture the “change.”