Why is my dependent's deduction only 1100

my 19 year old was a high school student for the first 5 months of 2020.  He received a1099-NEC for about 8400.  We claimed him as a dependent.  I am working on his taxes and turbotax deluxe is giving him a standard deduction of 1100.  So he is having to pay over 700 in taxes.  I read that the deduction was his income plus 350 (or was it 250?) or 1100, whichever is higher.  So I'm a bit confused.  I'm wondering if I went wrong somewhere lol.  Please help... and thanks for the help.