As per Ars Technica, Verizon's early 5G is easily blocked by obstacles such as walls. As such, the lack of coverage shouldn't really come as a surprise. 5G is, after all, still a technology in development.

However, the fact that Verizon is having trouble providing strong 5G coverage in stadiums isn't a great sign — especially as the company announced in February that it plans to roll out 5G to 30 cities this year.