See IRS Pub 525, page 11 which indicates that the total amount of the excess deferral is to be included on form 1040, line 1a (as if the money was never deferred from your wages) and the loss is to be included as a negative number on Schedule 1, line 8z: https://www.irs.gov/pub/irs-pdf/p525.pdf
With regard to entering into TurboTax, enter the Form 1099-R as is which TurboTax will include on Form 1040, line 1a. So that the remaining amount of the excess deferral is also included on line 1a, enter the amount of the loss into TurboTax as a positive amount of Miscellaneous income -> Other income not already reported on a W-2. Also enter the loss as a negative amount of Miscellaneous income -> Other reportable income and identified as "Loss on Excess Deferral Distribution" so that it is included on Schedule 1, line 8z, to be subtracted from your taxable income.
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