Being underestimated is a head start once you stop arguing with it.

Low expectations come with real advantages, as long as you are not spending your energy trying to correct them. Nobody is watching closely, nobody has predicted anything you have to live up to, and whatever you do next gets measured against almost nothing. The trap is the arguing: trying to convince people in advance uses up exactly the time that would have changed their minds anyway.

Let the misreading stand and go and do the work quietly. Pick one thing you are supposedly not capable of and get measurably better at it over the next month. Results end the argument without you having to make it.