Why is my standard deduction $2,233 if I am filing single and not the $12,200?

Are you someone else's dependent?

The standard deduction amount for an individual who may be claimed as a dependent by another taxpayer cannot exceed the greater of $1,100 or the sum of $350 and the individual’s earned income (not to exceed the regular standard deduction amount).

One possible explanation is that you are a dependent of another taxpayer.

If you can be claimed as a dependent by another taxpayer, your standard deduction for 2020 is limited to the greater of: (1) $1,100, or (2) your earned income plus $350 (but the total can't be more than the basic standard deduction for your filing status).