I believe Turbotax made an error calculating my Standard Deduction on line 12 of my completed 1040 form. The line 12 amount shows $30.594. Shouldn't this be $28,600?

This is a duplicate post, but it sounds like Line 12 is using Itemized deductions, since they are higher than the Standard one.  Line 12 is Standard deduction or itemized deductions (from Schedule A).

The standard deduction is a fixed amount based on your filing status, age and/or being blind.

Married Filing Jointly - $24,800 add $1,300 for each spouse age 65 or older and/or being blind

So the Standard Deduction for MFJ with both over age 65 would be $27,400 and if both also blind $30,000

Check your tax return to see if you have a Schedule A with itemized deductions totaling $30,594