The District of Columbia is not a state. Therefore, it cannot have citizens - only temporary residents. Those temporary residents are citizens of the state in which they resided prior to coming to the District of Columbia. Therefore, they should vote in those states - by absentee ballot if necessary.
It has citizens, just not statehood.
Well, I can see the point that many people living there were born and raised there, thus do not have a home state elsewhere.
They can accomplish this by giving back the parts of DC with people living there to Maryland. Then they don’t have to add a House seat with a DC rep.
And adding the House seat is just the camel nose in the tent, because eventually they would want to give DC two senators, as if it were a state.
Hope they nip this in the bud.