Don't confuse the amount of contribution returned with the amount distributed. To accomplish the return of the particular amount, a smaller amount was distributed due to the loss in value in the account during the computation period. Your excess contribution was still the higher amount and was the amount of contribution returned.
For example, if you contributed an excess $100 and the value of the account dropped 10% between the time the $100 was deposited and the corrective distribution was made, a distribution of $90 accomplishes a return of the $100 contribution.
IRS Pub 525 says that you can claim the difference as a loss by entering a negative amount on Schedule 1 line 8z as "Loss on Excess Deferral Distribution." That entry is made in TurboTax under Wages & Income -> Less Common Income -> Miscellaneous Income, 1099-A, 1099-C -> Other reportable income.
