in 2020, I hope what you mean is you filed your own tax return and checked the box that you CAN be claimed by someone else.
in 2021, did you check that same box? if no, what circumstances changed to think you CAN not be claimed by someone else. Just having a summer job doesn't do it. note that whether your parents claimed you or not is immaterial to the question you are asked. the question, CAN you be claimed, doesn't change based on your parents action.
before you begin amending, suggest getting that part straightneed out .....
you would have to file in each state where you earned income and then in CA (where you'll get a credit for taxes paid to other states)
Each year would have to be completed separately ; can't combine 2020 and 2021 in any way.
