it's simple..... when you fill out your tax return it will ask a series of questions, one of which is CAN YOU be claimed by someone else - answer 'no' to that question.
However, there are a number of rules that define if you CAN be claimed by someone else.... Whether your mother decides not to claim you is her right, but it doesn't change the answer to the question CAN she claim you.
you state you support yourself. Do make more than $4300 in 2020? Are you NOT in school? If so, then she CANNOT claim you and you are 'good to go'.
