No, they can't claim you. The qualifying child status for claiming a dependent dies at age 19 unless the dependent to be claimed is a full-time student, in which case it gets extended to age 24 or the child is permanently and fully disabled. You aren't a full-time student, ergo you don't pass the qualifying child test. Legally, they would be committing tax fraud by claiming you as a dependent.
Show them this:
https://www.irs.gov/pub/irs-news/fs-05-07.pdfif they try to argue with you about it
🙂
