At launch, Verizon says fans will mostly be able to take advantage of its 5G network while in the seating area of each stadium. A lot of that has to do with the nature of mmWave spectrum Verizon is using. Unlike LTE and Sub-6GHz, mmWave often can't penetrate hard surfaces like concrete. Its range is also minimal. Those disadvantages are what makes a stadium deployment so appealing to carriers that want to sell consumers on 5G. Open-air sports stadiums are one of the few places where a mmWave deployment makes sense since there's enough density to justify building out all the small cells that are required to blanket even a small area with 5G coverage.
https://www.engadget.com/2019/09/05/...-nfl-stadiums/