Can Milwaukee challenge its census population data drop?

August 14, 2021 update: Mayor Barrett says an appeal of the census data is under consideration: 

Less than 24 hours after the results were released, Barrett said he may file an appeal after the city of Milwaukee recorded it lost about 17,000 people over the last decade. 

"We went through this a decade ago where we felt the numbers were too low and we had a successful appeal, so we're examining that right now," said Barrett. 

I know from my previous work in Milwaukee city hall that census data can be challenged by a local government if it has its own data to show.

In anticipation of census processes which undercount low-income and communities of color, the city supplemented the federal counting effort with surveys and door-to-door work of its own authorized budgetary by the Common Council and carried out by contractors coordinated with the Department of Administration. 

Adequate population-based representation at the state and federal level along with allocation of millions of dollars in grants which the city 

needs as already-dwindling state shared revenue continues to fall depends on having the best data possible, so the question is whether Milwaukee carried out its own supplementary work and has numbers in hand that are ready to appeal this troubling published finding?

I seem to remember at least one prior successful challenge; anyone out there from the '90 census have anything to offer?