IRA custodians do not identify what portion of the distribution was a QCD. They simply report the distribution total. It's your responsibility to identify the portion that is QCD and report it appropriately on your tax return. That's done by excluding the QCD amount from Form 1040 line 4b (and Form 8606 line 7 if you are required to file Form 8606) and include the notation "QCD" next to line 4b. TurboTax does this automatically when you tell TurboTax how much to the distribution was sent from the IRA to charity.
Note that for those with a birthdate between July 1, 1949 and June 30, 1950, 2020 TurboTax presently (now version R17) has a bug the prevents it from asking the necessary question regard transfer of the distribution to charity. As a workaround for this, with the CD/download version you can provide the QCD-amount information on the 1099-R in forms mode or in any version of TurboTax you can temporarily change your birthdate in TurboTax to something before July 1, 1949, edit the 1099-R form in TurboTax and answer the question asking how much was transferred to charity, then change your birthdate back in TurboTax back to your actual birthdate.