Notice the flags are just copy and paste jobs. The artist wants the audience to understand that war propaganda is just an oversaturated, cheap reproduction of a simple template. That the choir of voices all telling you the same thing is nothing but an illusion. It's all just one voice, copy and pasted all over.

The Simpsons seemingly exist inside a void, staring blankly at you as you stare blankly into the emptiness of their expressions. It is frightening. Confronting! It dares the viewer to face what he may not want to: That there is nothing there! It's all a lie.

Once you look beyond Marge, the focal point, you notice that something is not quite right. The drawing becomes cruder towards the edges, as propaganda tends to look when you look more closely into the details and circumstances. This also creates the impression (quite deliberately) that the artist gave up on this assignment, his professional self-respect, and life in general. Like he wants to say: Please Xi Jinping! The Simpsons yearn for freedom!