why still "免征點隻有1250", see your own post.

Dependents – If you can be claimed as a dependent by another taxpayer, your standard deduction for 2023 is limited to the greater of: (1) $1,250, or (2) your earned income plus $400 (but the total can't be more than the basic standard deduction for your filing status).

https://www.irs.gov/taxtopics/tc551#:~:text=Dependents%20–%20If%20you%20can%20be,deduction%20for%20your%20filing%20status).