A dark mirror shows features one would rather not see. You gaze at the repulsive visage in the picture frame, the caricature of everything despicable, only to realize with dawning horror that you are looking not at a portrait but at a mirror.
The political defeat of Donald Trump in the 2020 election is a crossroads for the quasi-political movement grouped loosely around the QAnon conspiracy myth and, more broadly, around Trump himself. Because the man and the movement were a dark mirror for the whole of society, it is also a crossroads for society.