If you’re critiquing something, you might say that you’re giving it “bonus points” for an aspect that wasn’t essential or part of your original grading scheme, but you liked and consider to add something to the work.
Please suggest a similar phrase to use for an aspect that, as with bonus points, wasn’t essential or part of your original grading scheme, but that you disliked and consider to detract from the work. I’ve tried “negative bonus points,” “bonus penalties,” and “penalty points,” but none of them sounds quite right.