For your consideration ...
I can't think of a single reason why either of those would be federally funded. Then the city should pay for it. Hold a bake sale or something.
One reason the Key Bridge is getting federal funding may be because that it is part of Dwight D. Eisenhower National System of Interstate and Defense Highways, commonly known as the Interstate Highway System. That and because incompetent Moore has mismanaged Maryland's budget, and the billions Hogan left in the State's savings account when he left, as well as frittering away money on stupid projects.
About the stadium. . . . The area known as Washington, D.C., is considered the "Federal District Washington", or The Federal District of Washington, D.C., which is the capital city of the United States and is under the jurisdiction of the US Congress. So they can build a stadium if they, Congress, wants to build a new stadium, whether we want them to or not.
Congress gets this authority from the US Constitution in Article I, Section 8, Clause 17: In part: This clause grants Congress the authority to exercise exclusive legislation over a federal district (not exceeding ten miles square) .... and to exercise like authority over .... and for the erection of ... other needful buildings. Whether we have a need to spend billions for "other needful buildings" such as a stadium in DC is very debatable.
The Federal District of Washington, D.C. is also the Military District of Washington.
Here is the shoulder sleeve insignia worn by those soldiers serving in units that are part of, the Military District of Washington, which is headquartered at Fort McNair in Washington DC. Missions of the units in the Military District of Washington include ceremonial tasks as well as a combat role in the defense of the National Capital Region.
The more you know . . . . .