Hello,

I hope you are doing fine, As you filled form for  improvement exams in class 12th CBSE 2021 and did not appeared in any of the exam then your previous year marksheet would be valid but if you had filled 3 subjects and appeared in any one or two of the exam and did not appeared in one subject then your 2 subject marks will be updated in your marksheet and rest of your subject marks will be from your previous marksheet.

I hope you find this information helpful. I wish you all the best for your future.

Good Luck