It seems DC cannot have statehood without the permission of MD. Read below to find out why.
Originally DC was formed from Maryland and Virginia land, but the Viriginia land was ceded back to Virginia in 1846. Thus, all of DC's current land was originally Maryland's land. And as noted above, there's already been a case (1793-1794) where a DC resident represented Maryland in the U.S. Congress.
Uriah Forrest (who lived in DC) represented Maryland in the U.S. House of Representatives. Up until 1801, people who lived in DC voted just like any other U.S. citizen (voting in either Virginia or Maryland, depending on where the DC land came from). However, the "Organic Act" passed by Congress in 1801 stripped DC residents of their rights to vote in Federal elections. In 1801 this didn't affect many people, but this 1801 law now affects hundreds of thousands of people. Given this strong historical precedent, it would make sense for DC residents to vote in Federal elections as Marylandians. Although a bill was passed in 1961 to give residents the right to vote in presidential elections we still lack proper congressional representation. DC Vote has more information on this)
Which leads us back to the thesis sentence: Although Maryland ceded the land of DC for purposes of creating a Federal capital district, there's evidence that Maryland never ceded that land for the purpose of creating another state. That's important, because states have to specifically okay the creation of another state from their land. Indeed, there's historical evidence that Maryland did not intend for another state to be created, since a DC resident has represented Maryland!
Credit to: David A. Wheeler
https://dwheeler.com/essays/dc-in-maryland.html