They cannot claim you as a "Qualifying Child" because you are over 18 and not a fulltime student.
They cannot claim you as a "Qualifying Relative" if your total income.in 2020,was more than $4300.
So, you can and should claim yourself, for 2020. And you should be eligible for the $1800 stimulus credit.
You can also claim an education credit, although you may not be eligible for the most generous credit, The American Opportunity Credit, if your parents claimed it the maximum 4 times, in the past.
