Traitor Pawn

I just wanted to quickly introduce the idea that sometimes our own pawns help the opponent more than us. Typically a pawn is worth around 1, but in those cases the pawn has some negative value. One of the most common such cases is when there is opposite side castling. Then you would often rather not have your pawns on the side of the board where the opponent is castled.

And now let us introduce the "traitor pawn:"

Another classic example (can you guess what opening this is from?)

one last example, which shows that this idea can arise in all sorts of positions: