Leave box 19 blank. Maryland is just telling you that you that future distributions will be fully taxable by the state of Maryland because all of of your picked-up contributions have been distributed.
Assuming that none of the distribution was rolled over to another retirement account, you can simply tell TurboTax that the distribution was all RMD and the entire RMD required from this plan. TurboTax asks RMD questions when you reach age 73 and some of these RMD questions are new for 2024.
