It's also not at all accurate. I decided to check a few places to see if the article was backed by facts, it wasn't. Biden vastly outperformed Clinton in every major metro in Texas, as well as here Denver in Colorado. He also did better in Orlando and Tampa, but not Miami (the Cuban-Americans came out big for Trump) Was slightly down in San Fran, about even in LA, but better in San Diego. In Wisconsin, Biden did do better in Milwaukee, but even more so in Madison. And in Minnesota Biden vastly outperformed Clinton in the Twin Cities, and even in Duluth, where Trump has several appearances.
The enthusiasm poll is meaningless. A lot of Bernie types maybe weren't excited to vote for Biden, but they weren't going to let a repeat of 2016 happen.
If there were irregularities, there would be evidence. There is none.