If you have unearned income (income not earned from working, which includes investments and unemployment compensation) then you are subject to the "Kiddie Tax", and your tax rate is based on your parent's tax information.
https://ttlc.intuit.com/community/income/help/what-is-the-kiddie-tax/00/25913
This has always been true but it is affecting more people than usual this year because many young people got enhanced unemployment benefits for the first time, and if you got UEC but were under age 24 and partly supported by your parents, you can be subject to this tax.
