report child's earned + unearned income, tax seems a bit high

Hi, my son who's 18 and full time student, has both earned income $600+ and unearned income $1304 from 2024. TurboTax asked us to file his tax separately, b/c we do not qualify to include his tax return in our jointly tax return. The tax calculated for him is around $150, this seems a bit too much for $600+ earned income plus $4 over the $1300 unearned income tax threshold. 

 

thx,

Song