Very new to ML. I am trying to create an anomaly detector. I have thousands of graphs like the one I have attached. I am interested in the pink line. If the pink line's behavior changes drastically from the overall pattern of the line (i.e. the black circle), the graph needs to be flagged. While I am only interested in the pink line's behavior, I have included the blue line because it seems in every graph when the pink line dips downwards, the blue line dips upward.
I was thinking to use KNN, but I am not sure.
Any tips or guidance would be very appreciated! Thanks :)