Two key points:
1) You must "live with" your parents for them to claim you under the "qualifying child" rules. "Live with" is tricky because they can consider that you "lived with" them if you are away for a temporary absence, and college is almost always considered a temporary absence. If you "live on your own" means a dorm paid for by your parents and you go home for summer, then you probably "live with them" for dependent purposes. If you have really moved out (changed voting registration, found a new church, got a new doctor, joined a bowling league, or did other things to establish that your "domicile" is where you live now and not your parents' house) then your absence is no longer temporary and you don't "live with them". If the IRS is forced to investigate, they will look at the facts of your particular situation in detail.
Also, you only have to live with your parents for half the year for them to be able to claim you, so you will almost always be counted as living with your parents in your senior year of HS/freshman year of college even if you permanently moved out in August to go to college.
If you don't live with your parents, they can't claim you if you have taxable income over $4200, no matter any other facts.
2) If you live with your parents, they can claim you as long as you don't provide more than half your own support. They don't have to provide it, as long as you don't provide more than half. You need to add up your total living costs (room and board, transportation, medical, clothing, entertainment, and tuition) and then add up how much you provide from your own funds. Include money you spend from your earnings or your savings. You can also include student loans you borrow in your name. Don't include grants, and don't include money you spend to support other people.
These two key points should be evaluated for each tax year. They might be able to claim you for 2019 but not for 2020.
Most importantly, if you and your parents file conflicting tax returns, the IRS will eventually investigate both of you. You all need to decide if the benefits of fighting over the dependent designation are worth the costs.
