You can rant all you want about how I’m arguing from authority (I’m not) or how you’re disagreeing rather than not understanding, but you keep literally saying you do not understand.
I am challenging you to actually justify your position, which you have not done so.
Your perception of the squares in the image is “subjective” because you are seeing the same light from both grey squares but perceiving it differently based on context. You are literally percieving the same objective physical phenomenon in two different subjective ways.
Why does something differing based upon context make it subjective? That would make it contextual. It's not the same physical phenomenon: one is a gray square in the context of a shadow, and the other is not. Those are not the same things.