One small suggestion: Maybe you can try to change the color scale for your heat maps, so the minima become more visible. It took me a while to understand why the arrows are pointing at those three points, because the colors look all very similar along that "arc". If your color scale was magenta at the minima, it would be much easier to understand.
I'll see if I can do something with this. I kept myself to the viridis color map and just log + clamp because I didn't want to misrepresent the data, but I think you're right.
